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A Data Guide for this study is available as a web page and for download. The National Longitudinal Study of Adolescent to Adult Health (Add Health), 1994-2008 [Public Use] is a longitudinal study of a nationally representative sample of U.S. adolescents in grades 7 through 12 during the 1994-1995 school year. The Add Health cohort was followed into young adulthood with four in-home interviews, the most recent conducted in 2008 when the sample was aged 24-32. Add Health combines longitudinal survey data on respondents' social, economic, psychological, and physical well-being with contextual data on the family, neighborhood, community, school, friendships, peer groups, and romantic relationships. Add Health Wave I data collection took place between September 1994 and December 1995, and included both an in-school questionnaire and in-home interview. The in-school questionnaire was administered to more than 90,000 students in grades 7 through 12, and gathered information on social and demographic characteristics of adolescent respondents, education and occupation of parents, household structure, expectations for the future, self-esteem, health status, risk behaviors, friendships, and school-year extracurricular activities. All students listed on a sample school's roster were eligible for selection into the core in-home interview sample. In-home interviews included topics such as health status, health-facility utilization, nutrition, peer networks, decision-making processes, family composition and dynamics, educational aspirations and expectations, employment experience, romantic and sexual partnerships, substance use, and criminal activities. A parent, preferably the resident mother, of each adolescent respondent interviewed in Wave I was also asked to complete an interviewer-assisted questionnaire covering topics such as inheritable health conditions, marriages and marriage-like relationships, neighborhood characteristics, involvement in volunteer, civic, and school activities, health-affecting behaviors, education and employment, household income and economic assistance, parent-adolescent communication and interaction, parent's familiarity with the adolescent's friends and friends' parents. Add Health data collection recommenced for Wave II from April to August 1996, and included almost 15,000 follow-up in-home interviews with adolescents from Wave I. Interview questions were generally similar to Wave I, but also included questions about sun exposure and more detailed nutrition questions. Respondents were asked to report their height and weight during the course of the interview, and were also weighed and measured by the interviewer. From August 2001 to April 2002, Wave III data were collected through in-home interviews with 15,170 Wave I respondents (now 18 to 26 years old), as well as interviews with their partners. Respondents were administered survey questions designed to obtain information about family, relationships, sexual experiences, childbearing, and educational histories, labor force involvement, civic participation, religion and spirituality, mental health, health insurance, illness, delinquency and violence, gambling, substance abuse, and involvement with the criminal justice system. High School Transcript Release Forms were also collected at Wave III, and these data comprise the Education Data component of the Add Health study. Wave IV in-home interviews were conducted in 2008 and 2009 when the original Wave I respondents were 24 to 32 years old. Longitudinal survey data were collected on the social, economic, psychological, and health circumstances of respondents, as well as longitudinal geographic data. Survey questions were expanded on educational transitions, economic status and financial resources and strains, sleep patterns and sleep quality, eating habits and nutrition, illnesses and medications, physical activities, emotional content and quality of current or most recent romantic/cohabiting/marriage relationships, and maltreatment during childhood by caregivers. Dates and circumstances of key life events occurring in young adulthood were also recorded, including a complete marriage and cohabitation history, full pregnancy and fertility histories from both men and women, an educational history of dates of degrees and school attendance, contact with the criminal justice system, military service, and various employment events, including the date of first and current jobs, with respective information on occupation, industry, wages, hours, and benefits. Finally, physical measurements and biospecimens were also collected at Wave IV, and included anthropometric measures of weight, height and waist circumference, cardiovascular measures such as systolic blood pressure, diastolic blood pressure, and pulse, metabolic measures from dried blood spots assayed for lipids, glucose, and glycosylated hemoglobin (HbA1c), measures of inflammation and immune function, including High sensitivity C-reactive protein (hsCRP) and Epstein-Barr virus (EBV). Datasets: DS0: Study-Level Files DS1: Wave I: In-Home Questionnaire, Public Use Sample DS2: Wave I: Public Use Contextual Database DS3: Wave I: Network Variables DS4: Wave I: Public Use Grand Sample Weights DS5: Wave II: In-Home Questionnaire, Public Use Sample DS6: Wave II: Public Use Contextual Database DS7: Wave II: Public Use Grand Sample Weights DS8: Wave III: In-Home Questionnaire, Public Use Sample DS9: Wave III: In-Home Questionnaire, Public Use Sample (Section 17: Relationships) DS10: Wave III: In-Home Questionnaire, Public Use Sample (Section 18: Pregnancies) DS11: Wave III: In-Home Questionnaire, Public Use Sample (Section 19: Relationships in Detail) DS12: Wave III: In-Home Questionnaire, Public Use Sample (Section 22: Completed Pregnancies) DS13: Wave III: In-Home Questionnaire, Public Use Sample (Section 23: Current Pregnancies) DS14: Wave III: In-Home Questionnaire, Public Use Sample (Section 24: Live Births) DS15: Wave III: In-Home Questionnaire, Public Use Sample (Section 25: Children and Parenting) DS16: Wave III: Public Use Education Data DS17: Wave III: Public Use Graduation Data DS18: Wave III: Public Use Education Data Weights DS19: Wave III: Add Health School Weights DS20: Wave III: Peabody Picture Vocabulary Test (PVT), Public Use DS21: Wave III: Public In-Home Weights DS22: Wave IV: In-Home Questionnaire, Public Use Sample DS23: Wave IV: In-Home Questionnaire, Public Use Sample (Section 16B: Relationships) DS24: Wave IV: In-Home Questionnaire, Public Use Sample (Section 16C: Relationships) DS25: Wave IV: In-Home Questionnaire, Public Use Sample (Section 18: Pregnancy Table) DS26: Wave IV: In-Home Questionnaire, Public Use Sample (Section 19: Live Births) DS27: Wave IV: In-Home Questionnaire, Public Use Sample (Section 20A: Children and Parenting) DS28: Wave IV: Biomarkers, Measures of Inflammation and Immune Function DS29: Wave IV: Biomarkers, Measures of Glucose Homeostasis DS30: Wave IV: Biomarkers, Lipids DS31: Wave IV: Public Use Weights Wave I: The Stage 1 in-school sample was a stratified, random sample of all high schools in the United States. A school was eligible for the sample if it included an 11th grade and had a minimum enrollment of 30 students. A feeder school -- a school that sent graduates to the high school and that included a 7th grade -- was also recruited from the community. The in-school questionnaire was administered to more than 90,000 students in grades 7 through 12. The Stage 2 in-home sample of 27,000 adolescents consisted of a core sample from each community, plus selected special over samples. Eligibility for over samples was determined by an adolescent's responses on the in-school questionnaire. Adolescents could qualify for more than one sample.; Wave II: The Wave II in-home interview surveyed almost 15,000 of the same students one year after Wave I.; Wave III: The in-home Wave III sample consists of over 15,000 Wave I respondents who could be located and re-interviewed six years later.; Wave IV: All original Wave I in-home respondents were eligible for in-home interviews at Wave IV. At Wave IV, the Add Health sample was dispersed across the nation with respondents living in all 50 states. Administrators were able to locate 92.5% of the Wave IV sample and interviewed 80.3% of eligible sample members. ; For additional information on sampling, including detailed information on special oversamples, please see the Add Health Study Design page. Add Health was developed in response to a mandate from the U.S. Congress to fund a study of adolescent health. Waves I and II focused on the forces that may influence adolescents' health and risk behaviors, including personal traits, families, friendships, romantic relationships, peer groups, schools, neighborhoods, and communities. As participants aged into adulthood, the scientific goals of the study expanded and evolved. Wave III explored adolescent experiences and behaviors related to decisions, behavior, and health outcomes in the transition to adulthood. Wave IV expanded to examine developmental and health trajectories across the life course of adolescence into young adulthood, using an integrative study design which combined social, behavioral, and biomedical measures data collection. Response Rates: Response rates for each wave were as follows: Wave I: 79 percent; Wave II: 88.6 percent; Wave III: 77.4 percent; Wave IV: 80.3 percent; Adolescents in grades 7 through 12 during the 1994-1995 school year. Respondents were geographically located in the United States. audio computer-assisted self interview (ACASI) computer-assisted personal interview (CAPI) computer-assisted self interview (CASI) paper and pencil interview (PAPI) face-to-face interview

Simulated Raman scattering spectra produced by non-linear pumping of a single-mode optical fiber. Here the input modulation is slowed to 2 Hz so that the changes to the output spectra can be seen.

Nigeria is estimated to account for 19% of all estimated global maternal deaths with approximately 58,000 in 2015. The high number is partly due to the inadequate access of women to evidence-based skilled pregnancy care. The Federal Ministry of Health (FMoH) and all major health policy agencies in Nigeria have recognized the need for increased access to skilled obstetric care, especially in rural areas, as critical to reducing the high rate of maternal mortality. However, despite the fact that policymakers recognize that primary health care should play a key role in improving rural women's access to skilled pregnancy care, Primary Health Centres (PHCs) are often poorly utilized throughout the country. This project is a 5-year (2015-2020) implementation research conducted by the Women's Health and Action Research Centre (WHARC), Benin City, Nigeria in collaboration with the University of Ottawa (UOttawa), Canada and with funding from the International Development Research Centre (IDRC), Global Affairs Canada (GAC) and the Canadian Institute for Health Research (CIHR) under the Innovating for Maternal and Child Health in Africa (IMCHA) Initiative. The project's specific objectives are: 1) to identify the demand and supply factors responsible for the use and non-use of PHCs for pregnancy care in Esan South East and Etsako East LGAs of Edo State, Nigeria; 2) based on Objective 1, to derive and implement a set of multi-faceted community-led interventions to increase women's access to skilled pregnancy care offered in PHCs in Esan South East and Etsako East Local Government Areas (LGA); and 3) to evaluate the effectiveness of the interventions using both indicators of access to services, as well as maternal and fetal/newborn health outcomes in the intervention communities. The study was conducted in Esan South East and Etsako East Local Government Areas (LGAs) in Edo State in southern Nigeria. Both LGAs are located in the rural and riverine areas of the state, adjacent to River Niger, with Estako East in the northern part of the Edo State part of the river, while Esan South East is in the southern part. Edo State is one of Nigeria’s thirty-six states. Each state consists of LGAs, and LGAs consist of political/health Wards. The study was originally designed to be a randomized control trial (Yaya et al., 2018) but was changed to a quasi-experiment separate sample pretest and posttest design. The change was necessitated by the difficulty in achieving reliable randomization in the study communities. The study was conducted in three phases. At phase one, a baseline was conducted using a mixed-method approach to address objective 1. Based on the results of the baseline research, a set of intervention activities were designed and implemented simultaneously in phase 2 for two years. Phase three was the endline research which addressed the study objective 3. Ethical approval for the study was obtained from the National Health Research Ethics Committee (NHREC) of Nigeria – protocol number NHREC/01/01/2007 – 10/04/2017; and written informed consent was obtained from individual respondent/participant, except in the community conversations where the consent was verbal. The data we are sharing contain baseline and endline data. collected through a mixed-method approach to address the study objectives. The baseline data were collected between July 29 to August 16, 2017, using a mixed-method that comprises a household survey, exit interview, PHC site assessment survey, community conversation, focus group discussion, and key informant interview. The endline data were collected between June 24 and July 6, 2020, using a household survey. All the data collection instruments were pretested and the data were collected by trained data collectors. Response Rates: The sample size for the baseline and end household survey was 1,318, to adjust for non-response, 10% was added to derive a total of 1,450. At baseline, 1408 responded, and at endline 1,411 responded. Based on replacement of non-response, the total number expected were covered during the two surveys bringing the response rate to be 100% Household survey: Multistage, systematic, random sampling design;Exit Interview: All eligible women were interviewed;Site Assessment survey: Random sampling;Qualitative data: Purposive and convenient sampling Ever married women age 15-45 years oldPrimary Health Centres. Smallest Geographic Unit: Local Government Area computer-assisted personal interview (CAPI); face-to-face interview;

Sample weights are available for analyzing NHANES 2003-2004 data. Most data analyses require either the interviewed sample weight (variable name: WTINT2YR) or examined sample weight (variable name: WTMEC2YR). The two-year sample weights (WTINT2YR, WTMEC2YR) should be used for NHANES 2003-2004 analyses. Use of the correct sample weight for NHANES analyses is extremely important and depends on the variables being used. A good rule of thumb is to use "the least common denominator" approach. With this approach, the analyst checks the variables of interest. The variable that was collected on the smallest number of persons is the "least common denominator," and the sample weight that applies to that variable is the appropriate one to use for that particular analysis. Please refer to the NHANES 2003-2004 Analytic Guidelines provided with the data release files to determine the appropriate analytic methodology. NCHS September 2006 Version--NHANES Analytic Guidelines Beginning in 1999, the National Health and Nutrition Examination Survey (NHANES) became a continuous, annual survey rather than the periodic survey that it had been in the past. For a variety of reasons, including disclosure and reliability issues, the survey data are released on public use data files every two years. Thus, the data release cycle for the ongoing (and continuous) NHANES is described as NHANES 1999-2000, NHANES 2001-2002, NHANES 2003-2004, etc. In addition to the analysis of data from any two-year cycle, it is possible to combine two or more "cycles" (e.g., 2003-2004 and 2005-2006) to create NHANES 2003-2006, thus increasing sample size and analytic options. In order to produce estimates with greater statistical reliability, combining two or more two-year cycles of the continuous NHANES is encouraged and strongly recommended. When combining cycles of data, it is extremely important that (1) the user verify that data items collected in all combined years were comparable in wording and methods and (2) use a proper sampling weight. Beginning in 2003, the survey content for each two year period is held as constant as possible to be consistent with the data release cycle. In the first four years of the continuous survey, this was not always the case, and some special data release and data access procedures had to be developed and used for selected survey content collected in "other than two-year" intervals (see the NHANES release policy). The decision on how many years of NHANES data are required for a particular analysis can be summarized by the concept of minimum sample size required. The minimum sample size is determined by the statistic to be estimated (e.g. mean, total, proportion...), the reliability criteria (e.g. 20 or 30 percent relative standard error), the Design Effect for the statistics (DEFF defined as the variance inflation factor), and the degrees of freedom for the standard error estimate. Earlier NHANES surveys were conducted for four or more years and, thus, have larger samples than a two-year cycle of the current continuous NHANES. However, in each of those surveys, many sub-domains did not meet minimum sample size requirements and in those cases the above concerns were (and still are) relevant. When combining two or more two-year cycles of the continuous NHANES, the user should use the following procedure for calculating the appropriate combined sample weights. When combining two or more two-year cycles of the continuous NHANES, the user must calculate new sample weights before beginning any analysis of the data. NCHS will not be calculating and including all possible combinations of multiple two-year cycles of the continuous survey because it would be impractical to produce them and include them on all public release files. Because of a particular issue with Census population estimates, a set of four-year weights was created for the first four years of the continuous NHANES -- 1999-2002. The sample weights for NHANES 1999-2000 were based on population estimates developed by the Bureau of the Census before the Year 2000 Decennial Census counts became available. The two-year sample weights for NHANES 2001-2002 were based on population estimates that incorporate the year 2000 Census counts. The two population estimates were not strictly comparable. To facilitate analysis for these first four years of the continuous NHANES, appropriate four-year sample weights (comparable to Census 2000 counts) were calculated and added to the demographic data files for both 1999-2000 and 2001-2002. These sample weights have the same variable name in each file. For example, for the sample persons for whom there are MEC data items, the variable name for the four-year weight is WTMEC4YR. Thus, users of the earlier release of the NHANES 1999-2000 demographic file must use the updated demographic file to appropriately analyze the combined four-year data 1999-2002. Because NHANES 2003-2004 uses the same year 2000 Census counts as were used for NHANES 2001-2002, there is no need to create special four-year weights for 2001-2004. For a four-year estimate for 2001-2004, one can create a new variable for a four-year weight by assigning half of the two-year weight for 2001-2002 if the person was sampled in 2001-2002 or assigning half of the two-year weight for 2003-2004 if the person was sampled in 2003-2004. This is possible because the two-year weights for 2003-2004 are comparable to the 2001-2002 weights (in terms of a population basis). For an estimate for the six years 1999-2004, a six-year weight variable can be created by assigning two-thirds of the four-year weight for 1999-2002 if the person was sampled in 1999-2002, or assigning one-third of the two-year weight for 2003-2004 if the person was sampled in 2003-2004. This is possible because the 2003-2004 weights are also comparable (on a population basis) to the combined four-year weights specifically created for 1999-2002. This information summarizes the most recent analytic and reporting guidelines that should be used for most NHANES analyses and publications. It is important for users to understand the entire document and to become familiar with statistical issues in the analysis of complex survey data. These suggested guidelines provide a framework to users for producing estimates that conform to the analytic design of the survey. Because statistical methods for analyzing complex survey data are continually evolving, these recommendations may differ slightly from those used by analysts for previous NHANES surveys. It is important to remember that the statistical guidelines in this document are not absolute. When conducting analyses, the analyst needs to use his/her subject matter knowledge (including methodological issues), as well as information about the survey design. The more one deviates from the original analytic categories and original analytic objectives defined in the planning documents, the more important it is to evaluate the results carefully and to interpret the findings cautiously. Future versions of the NHANES Analytic and Reporting Guidelines will include additional topics, such as sample sizes and response rates for each NHANES survey, hypothesis testing, multivariate analysis, and a discussion of the concept of statistical versus practical significance. These are Guidelines not standards. Depending upon the subject matter and statistical efficiency, specific analyses may depart from these guidelines; but the burden of proof for statistical efficiency and for appropriate data interpretation is on the data user/analyst. Again, NHANES data files from the continuous survey are publicly released on a two-year basis (1999-2000, 2001-2002, 2003-2004, etc.) and as small, content specific files. The data files and associated documentations, as well as these analytic guidelines, may be edited and/or updated to reflect new data release files. Users should periodically check the NHANES website to determine if any new or revised data files have been released and if these analytic guidelines have been updated. Datasets: DS0: Study-Level Files DS1: Demographics DS11: Examination: Audiometry (Subsample) DS12: Examination: Audiometry Tympanometry DS13: Examination: Balance DS14: Examination: Bioelectrical Impedance DS15: Examination: Blood Pressure DS16: Examination: Body Measurements DS17: Examination: Cardiovascular Fitness DS18: Examination: Composite International Diagnostic Interview (Generalized Anxiety Disorder) (Subsample) DS19: Examination: Composite International Diagnostic Interview (Major Depression Module) (Subsample) DS20: Examination: Composite International Diagnostic Interview (Panic Disorder Module) (Subsample) DS21: Examination: Dermatology DS22: Examination: Dietary Interview (Individual Foods File -- First Day) DS23: Examination: Dietary Interview (Individual Foods File -- Second Day) DS24: Examination: Dietary Interview (Total Nutrient Intakes -- First Day) DS25: Examination: Dietary Interview (Total Nutrient Intakes -- Second Day) DS26: Examination: Dual Energy X-Ray Absorptiometry (DXX) DS27: Examination: Dual Energy X-Ray Absorptiometry Supplemental (DXX_S) DS28: Examination: Food Frequency Questionnaire -- Raw Questionnaire Responses DS29: Examination: Food Frequency Questionnaire -- DietCalc Output DS30: Examination: Lower Extremity Ankle Brachial Blood Pressure Index DS31: Examination: Lower Extremity Disease (Peripheral Neuropathy) DS32: Examination: Oral Health (Addendum) DS33: Examination: Oral Health (Dentition) DS34: Examination: Oral Health (Lower Periodontal) DS35: Examination: Oral Health (Upper Periodontal) DS36: Examination: Oral Health (Recommendation of Care/Referral) DS37: Examination: Physical Activity Monitor DS38: Examination: Vision Exam DS101: Laboratory: Antibody to Coxiella Burnetii (Q-Fever) (Surplus Sera) DS102: Laboratory: Antibody to Cytomegalovirus IgG (Surplus Sera) DS103: Laboratory: Antibody to Mumps (Surplus Sera) DS104: Laboratory: Melamine (Surplus Urine) DS105: Laboratory: Varicella-Zoster Virus Antibody (Surplus Sera) DS106: Laboratory: Lab 02 Hepatitis DS107: Laboratory: Lab 02 Hepatitis B Surface Antibody DS108: Laboratory: Lab 02 Hepatitis A Antibody DS109: Laboratory: Lab 03 Human Immunodeficiency Virus DS110: Laboratory: Lab 04 Urinary Perchlorate DS111: Laboratory: Lab 04 Volatile Organic Compounds In Blood And Water DS112: Laboratory: Lab 05 Chlamydia Trachomatis And Neisseria Gonorrhea DS113: Laboratory: Lab 06 Acrylamide And Glycidamide DS114: Laboratory: Lab 06 Blood Lead, Cadmium And Mercury DS115: Laboratory: Lab 06 Methylmalonic Acid And Homocysteine DS116: Laboratory: Lab 06 Rbc Folate, Serum Folate, And Vitamin B12 DS117: Laboratory: Lab 06 Serum Cotinine DS118: Laboratory: Lab 06 Ferritin And Transferrin Receptor DS119: Laboratory: Lab 06 Heavy Metals DS120: Laboratory: Lab 06 Urinary Iodine DS121: Laboratory: Lab 06 Urinary Phytoestrogens DS122: Laboratory: Lab 06 Urinary Total Arsenic And Speciated Arsenics DS123: Laboratory: Lab 06 Urinary Mercury DS124: Laboratory: Lab 06 Vitamin C DS125: Laboratory: Lab 06 Vitamin D DS126: Laboratory: Lab 09 Herpes I And Herpes II DS127: Laboratory: Lab 10 Glycohemoglobin DS128: Laboratory: Lab 10AM Glucose, C-Peptide, Insulin DS129: Laboratory: Lab 11 CRP DS130: Laboratory: Lab 11 PSA DS131: Laboratory: Lab 13 Total Cholesterol And HDL Cholesterol DS132: Laboratory: Lab 13AM Triglycerides And LDL Cholesterol DS133: Laboratory: Lab 16 Urinary Albumin DS134: Laboratory: Lab 17 Toxoplasma (IgG and IgM) DS135: Laboratory: Lab 19 Measles Rubella And Varicella DS136: Laboratory: Lab 20 Lead Dust DS137: Laboratory: Lab 24 Environmental Pesticides DS138: Laboratory: Lab 24 Environmental Phenols DS139: Laboratory: Lab 24 Polyfluorinated Compounds DS140: Laboratory: Lab 24 Urinary Phthalates DS141: Laboratory: Lab 25 Complete Blood Count DS142: Laboratory: Lab 26 Urinary Current Use Pesticide DS143: Laboratory: Lab 26 Urinary Organophosphate Insecticides DS144: Laboratory: Lab 28 Dioxins, Furans, and Coplanar PCBS DS145: Laboratory: Lab 28 Non-Dioxin-Like Polychlorinated Biphenyls DS146: Laboratory: Lab 28 Organochlorine Pesticides DS147: Laboratory: Lab 28 Polybrominated Diphenyl Ethers DS148: Laboratory: Lab 31 Polyaromatic Hydrocarbons DS149: Laboratory: Lab 34 Trichomonos, Vaginalis And Bacterial Vaginosis DS150: Laboratory: Lab 35 Methicillin Resistant Staphylococcus Aureus DS151: Laboratory: Lab 36 Syphilis IgG, RR and TP-PA DS152: Laboratory: Lab 37 Human Papillomavirus (HPV) DNA Hybrid Capture, PCR, and Hybridization Results from Vaginal Swab Samples DS153: Laboratory: Lab 39 Erythrocyte Protoporphyrin And Selenium DS154: Laboratory: Lab 40 Biochemistry Profile DS155: Laboratory: Lab 40 Iron, TIBC and Transferrin DS156: Laboratory: Lab 43 Vitamin B6 DS157: Laboratory: Lab 45 Vitamin A, E And Carotenoids DS158: Laboratory: Lab 52 HPV Serum DS159: Laboratory: Phlebotomy Fasting Questions DS160: Laboratory: Urine Collection (Pregnancy) DS201: Questionnaire: Acculturation DS202: Questionnaire: Alcohol Use DS203: Questionnaire: Analgesics Pain Relievers DS204: Questionnaire: Audiometry DS205: Questionnaire: Balance DS206: Questionnaire: Blood Pressure DS207: Questionnaire: Cardiovascular Disease And Health DS208: Questionnaire: Current Health Status DS209: Questionnaire: Dermatology DS210: Questionnaire: Diabetes DS211: Questionnaire: Diet Behavior And Nutrition DS212: Questionnaire: Dietary Supplement Use - Supplement Counts DS213: Questionnaire: Dietary Supplement Use - Participants Use Of Supplement DS214: Questionnaire: Dietary Supplement Use - Supplement Information DS215: Questionnaire: Dietary Supplement Use - Ingredient Information DS216: Questionnaire: Dietary Supplement Use - Supplement Blend DS217: Questionnaire: Drug Use DS218: Questionnaire: Early Childhood DS219: Questionnaire: Family Smoking DS220: Questionnaire: Food Security DS221: Questionnaire: Health Insurance DS222: Questionnaire: Hepatitis C Follow Up Questionnaire DS223: Questionnaire: Hospital Utilization DS224: Questionnaire: Housing Characteristics DS225: Questionnaire: Immunization DS226: Questionnaire: Kidney Conditions - Urology DS227: Questionnaire: Medical Conditions DS228: Questionnaire: Miscellaneous Pain DS229: Questionnaire: Occupation DS230: Questionnaire: Oral Health DS231: Questionnaire: Osteoporosis DS232: Questionnaire: Pesticide Use DS233: Questionnaire: Physical Activity DS234: Questionnaire: Physical Activity Individual Activities File DS235: Questionnaire: Physical Functioning DS236: Questionnaire: Prescription Medications DS237: Questionnaire: Drug Information DS238: Questionnaire: Prostate Conditions DS239: Questionnaire: Prostate Specific Antigen Follow Up Questionnaire DS240: Questionnaire: Reproductive Health DS241: Questionnaire: Respiratory Health And Disease DS242: Questionnaire: Smoking And Tobacco Use DS243: Questionnaire: Smoking And Tobacco Use (MEC) DS244: Questionnaire: Social Support DS245: Questionnaire: Sexual Behavior DS246: Questionnaire: Vision DS247: Questionnaire: Weight History The most recent series of data collection waves for NHANES began in 1999. Every year, approximately 7,000 individuals, of all ages, are interviewed in their homes and of these, approximately 5,000 complete the health examination component of the survey. A majority of the health examinations are conducted in mobile examination centers (MECs). The MECs provide an ideal setting for the collection of high quality data in a standardized environment. In addition to the MEC examinations, a small number of survey participants receive an abbreviated health examination in their homes if they are unable to come to the MEC. The NHANES target population is the civilian, noninstitutionalized United States population. NHANES 2003-2004 includes over-sampling of low-income persons, adolescents 12-19 years of age, persons 60 years of age and older, African Americans, and Mexican Americans. Initially, households are identified for inclusion in the NHANES sample and an advance letter is mailed to each address informing the occupant(s) that an NHANES interviewer will visit their home. The household interview component is comprised of Screener, Sample Person, and Family interviews, each of which has a separate questionnaire (please refer to the data file documentation). Trained household interviewers administer all of the questionnaires. In most cases, the interview setting was the survey participant's home. The interview data are recorded using the Blaise computer-assisted personal interview (CAPI) system. When the interviewer arrives at the home, he or she shows an official identification badge and briefly explains the purpose of the survey. If the occupant has not seen the advance letter, a copy is given to them to read. The interviewer requests that the occupant answer a brief questionnaire to determine if any household occupants are eligible to participate in NHANES. If eligible individuals are identified, the interviewer proceeds with efforts to recruit these individuals. Initially, the interviewer explains the household questionnaires to all eligible participants 16 years of age and older, informs the potential respondents of their rights, and provides assurances about the confidentiality of the survey data (reiterating what is stated in the advance letter). A majority of the household interviews are conducted during the first contact. If this is inconvenient for the survey participant, an appointment is made to administer the household interview questionnaires later. Household interviews for survey participants under 16 years of age are conducted with a proxy (usually their parent or guardian). If there is no one living in the household who is over 16, participants under 16 years of age are permitted to self-report. Respondents are asked to sign an Interview Consent Form agreeing to participate in the household interview portion of the survey. For participants 16-17 years of age a parent or guardian consents and the child gives his/her assent. After the household interview is completed, the interviewer reviews a second informed consent brochure with the participant. This brochure contains detailed information about the NHANES health examination component. All interviewed persons are asked to complete the health examination component. Those who agree to participate are asked to sign additional consent forms for the health examination component. The interviewer telephones the NHANES field office from the participant's home to schedule an appointment for the examination. The interviewer informs the participants that they will receive remuneration as well as reimbursement for transportation and childcare expenses, if necessary. Target Populations There are different target population groups for the topics within and between NHANES questionnaire sections. For example, in the Nutrition and Diet Behavior section, questions pertaining to infant nutrition and breast-feeding were asked of proxy respondents for children 6 years of age and younger, alcohol consumption frequency questions were asked of persons 20 years of age and older, and senior meal program participation questions were asked of respondents 60 years of age and older. Data users should review the survey questionnaire codebooks thoroughly to determine the target populations for each NHANES questionnaire section and sub-section. The NHANES Health Examination Component When a participant arrives at the MEC, the MEC Coordinator greets the participant and verifies all pertinent identifier information. Each participant receives a disposable paper gown and a pair of slippers to wear during their examination. Persons six years of age and older are asked to provide a urine specimen. MEC staff direct participants to the rooms where the examination components are conducted. In addition to the MEC Coordinator, each MEC survey team consists of one physician, one dentist, two dietary interviewers, three certified medical technologists, five health technicians, one phlebotomist, two interviewers and one computer data manager. Upon completion of the examination, each examinee is remunerated. Some of the medical findings from the examination are given to the examinees before they leave the MEC. The other reportable survey findings are mailed to participants after the laboratory assays and special tests are completed. MEC Operations Three MECs are equipped for use in NHANES. Each MEC consists of four large, inter-connected trailer units. An advance team sets up the MECs prior to the start of the survey examinations. Water, sewer, electrical, and communication lines are connected during set-up. The MEC equipment and data collection systems must be checked and calibrated prior to the start of survey data collection. The MECs are open a total of five days per week, and the nonoperational days change on a rotating basis so that appointments can be scheduled on any day of the week. Two examination sessions are conducted daily. For the convenience of the survey participants, appointments can be scheduled during morning, afternoon, or evening hours. The examinations require up to three hours to complete. At any given time during the survey, examinations are conducted at two survey locations simultaneously. Staff vacations are scheduled for periods of about one month at New Years and about two weeks during the summer, leaving ten and one-half months to conduct examinations. Home Examinations Participants who are 50 years and older or less than 1 year old and are unable or unwilling to travel to the MEC were offered a home examination administered by an examiner from the MEC. The National Health and Nutrition Examination Surveys (NHANES) is a program of studies designed to assess the health and nutritional status of adults and children in the United States. The NHANES combines personal interviews and physical examinations, which focus on different population groups or health topics. These surveys have been conducted by the National Center for Health Statistics (NCHS) on a periodic basis from 1971 to 1994. In 1999 the NHANES became a continuous program with a changing focus on a variety of health and nutrition measurements which were designed to meet current and emerging concerns. The surveys examine a nationally representative sample of approximately 5,000 persons each year. These persons are located in counties across the United States, 15 of which are visited each year. For NHANES 2003-2004, there were 12,761 persons selected for the sample, 10,122 of those were interviewed (79.3 percent) and 9,643 (75.6 percent) were examined in the mobile examination centers (MEC). Many of the NHANES 2003-2004 questions were also asked in NHANES II 1976-1980, Hispanic HANES 1982-1984, NHANES III 1988-1994, and NHANES 1999-2002. New questions were added to the survey based on recommendations from survey collaborators, NCHS staff, and other interagency work groups. As in past health examination surveys, data were collected on the prevalence of chronic conditions in the population. Estimates for previously undiagnosed conditions, as well as those known to and reported by survey respondents, are produced through the survey. Risk factors, those aspects of a person's lifestyle, constitution, heredity, or environment that may increase the chances of developing a certain disease or condition, were examined. Data on smoking, alcohol consumption, sexual practices, drug use, physical fitness and activity, weight, and dietary intake were collected. Information on certain aspects of reproductive health, such as use of oral contraceptives and breastfeeding practices, were also collected. The diseases, medical conditions, and health indicators that were studied include: anemia, cardiovascular disease, diabetes and lower extremity disease, environmental exposures, equilibrium, hearing loss, infectious diseases and immunization, kidney disease, mental health and cognitive functioning, nutrition, obesity, oral health, osteoporosis, physical fitness and physical functioning, reproductive history and sexual behavior, respiratory disease (asthma, chronic bronchitis, emphysema), sexually transmitted diseases, skin diseases, and vision. The sample for the survey was selected to represent the United States population of all ages. Special emphasis in the 2003-2004 NHANES was on adolescent health and the health of older Americans. To produce reliable statistics for these groups, adolescents aged 15-19 years and persons aged 60 years and older were over-sampled for the survey. African Americans and Mexican Americans were also over-sampled to enable accurate estimates for these groups. Several important areas in adolescent health, including nutrition and fitness and other aspects of growth and development, were addressed. Since the United States has experienced dramatic growth in the number of older people during the twentieth century, the aging population has major implications for health care needs, public policy, and research priorities. NCHS is working with public health agencies to increase the knowledge of the health status of older Americans. NHANES has a primary role in this endeavor. In the examination, all participants visit the physician who takes their pulse or blood pressure. Dietary interviews and body measurements are included for everyone. All but the very young have a blood sample taken and see the dentist. Depending upon the age of the participant, the rest of the examination includes tests and procedures to assess the various aspects of health listed above. Usually, the older the individual, the more extensive the examination. Some persons who are unable or unwilling to come to the examination center may be given a less extensive examination in their homes. Demographic data file variables are grouped into three broad categories: (1) Status Variables: provide core information on the survey participant. Examples of the core variables include interview status, examination status, and sequence number. (Sequence number is a unique ID assigned to each sample person and is required to match the information on this demographic file to the rest of the NHANES 2003-2004 data). (2) Recoded Demographic Variables: these variables include age (age in months for persons through age 19 years, 11 months; age in years for 1- to 84-year-olds, and a top-coded age group of 85 years of age and older), gender, a race/ethnicity variable, current or highest grade of education completed, (less than high school, high school, and more than high school education), country of birth (United States, Mexico, or other foreign born), Poverty Income Ratio (PIR), income, and a pregnancy status variable (adjudicated from various pregnancy related variables). Some of the groupings were made due to limited sample sizes for the two-year data set. (3) Interview and Examination Sample Weight Variables: sample weights are available for analyzing NHANES 2003-2004 data. For a complete listing of survey contents for all years of the NHANES see the document -- Survey Content -- NHANES 1999-2010. audio computer-assisted self interview (ACASI), computer-assisted personal interview (CAPI), computer-assisted self interview (CASI), face-to-face interview, on-site questionnaire NCHS provides continuous updates/new data notification, as well as other important information for the NHANES. It is recommended that users of these data sign up for the information through the NHANES Listserv. The "What's New" page on the NHANES Web site provides updates/new information which may not be included in the listserv emails. Further, not all documentation files are included with this ICPSR release and may be found at the NHANES 2003-2004 Web site. In preparing the data files for this collection, the National Center for Health Statistics (NCHS) has removed direct identifiers and characteristics that might lead to identification of data subjects. As an additional precaution NCHS requires, under Section 308(d) of the Public Health Service Act (42 U.S.C. 242m), that data collected by NCHS not be used for any purpose other than statistical analysis and reporting. NCHS further requires that analysts not use the data to learn the identity of any persons or establishments and that the director of NCHS be notified if any identities are inadvertently discovered. ICPSR member institutions and other users ordering data from ICPSR are expected to adhere to these restrictions. Many variables that are listed in the Demographic questionnaire sections of the Household Interview were omitted (by NCHS) from this data release due to concerns about participant confidentiality. NCHS did not include confidential and administrative data in this release and further, some variables have been recoded or top-coded to protect the confidentiality of survey participants. Many of the NHANES 2003-2004 questions were also asked in NHANES II, 1976-1980, Hispanic HANES 1982-1984, and NHANES III, 1988-1994. New questions were added to the survey based on recommendations from survey collaborators, NCHS staff, and other interagency work groups. NHANES 2003-2004 survey design and demographic variables are found in Part 1 Demographics file in this release. All of the data files can be linked by using the common survey participant identification number (variable name: SEQN). Merging information from multiple NHANES 2003-2004 data files using SEQN ensures that the appropriate information for each survey participant is linked correctly. All data files should be sorted by SEQN. The NHANES 2003-2004 data files do not have the same number of records in each file. For example, there are different numbers of subjects in the Interview and Examination samples of the survey. Additionally, the number of records in each data file varies depending on gender and age profiles for the specific component(s). The sample person demographic file is composed of a limited set of core variables that are required to analyze NHANES 2003-2004 data. Per agreement with NCHS, ICPSR distributes the data file(s) and text of the technical documentation for this collection as prepared by NCHS. IMPORTANT NOTE CONCERNING THE AVAILABILITY OF DATA FILES: Dataset 37 is so large that it exceeds the software limitations for the Stata data file format (file extension .dta) and SAS Cport Transport file format (file extension .stc). As such, these files are not available. Users requiring these files are encouraged to utilize the ASCII version of the data file, along with the appropriate setup file for the desired software package. However, the setup file may need to be edited so that only a subset of the data is accessed, in an effort to avoid exceeding the software limitations. All data files have been merged with the demographics file with the exception of those parts that did not contain the linking variable SEQN, which are as follows: Questionnaire: Dietary Supplement Use - Supplement Information (Part 214), Questionnaire: Dietary Supplement Use - Ingredient Information (Part 215), Questionnaire: Dietary Supplement Use - Supplement Blend (Part 216), and Questionnaire: Drug Information (Part 237). Within the Oral Health (Dentition) File Part 33 variables "OHX02CSC through OHX15CSC and OHX18CSC through OHX31CSC, as well as OHX02SE, OHX03SE, OHX14SE, OHX15SE, OHX18SE, OHX19SE, OHX30SE, and OHX31SE" the NCHS coded multiple conditions per record. Users should consult the documentation and review the labeling of the variables in question for further information. The user guides that are presently available are comprised of documentation from the NCHS. These user guides do not reflect the merging of each file with the demographics file, as this was done by ICPSR staff. The old .tsv and .txt files have been taken down. The NHANES survey design is a stratified, multistage probability sample of the civilian noninstitutionalized United States population. The stages of sample selection are: (1) selection of Primary Sampling Units (PSUs) which are counties or small groups of contiguous counties, (2) segments within PSUs (a block or group of blocks containing a cluster of households), (3) households within segments, and (4) one or more participants within households. A total of 15 PSUs are visited during a 12-month time period. Details of the design and content of each survey are available at the NHANES Web site. ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major statistical software formats as well as standard codebooks to accompany the data. In addition to these procedures, ICPSR performed the following processing steps for this data collection: Performed consistency checks.; Created variable labels and/or value labels.; Standardized missing values.; Checked for undocumented or out-of-range codes.. The NHANES target population is the civilian, noninstitutionalized United States population. National Health and Nutrition Examination Survey (NHANES) and Followup Series Presence of Common Scales: DISC -- Predictive Scale

Supplemental material, Supplementary_Figure_4 for Comparing CST Lesion Metrics as Biomarkers for Recovery of Motor and Proprioceptive Impairments After Stroke by Sonja E. Findlater, Rachel L. Hawe, Erin L. Mazerolle, Abdulaziz S. Al Sultan, Jessica M. Cassidy, Stephen H. Scott, G. Bruce Pike and Sean P. Dukelow in Neurorehabilitation and Neural Repair

Downloads of Add Health require submission of the following information, which is shared with the original producer of Add Health: supervisor name, supervisor email, and reason for download. A Data Guide for this study is available as a web page and for download. The National Longitudinal Study of Adolescent to Adult Health (Add Health), 1994-2018 [Public Use] is a longitudinal study of a nationally representative sample of U.S. adolescents in grades 7 through 12 during the 1994-1995 school year. The Add Health cohort was followed into young adulthood with four in-home interviews, the most recent conducted in 2008 when the sample was aged 24-32. Add Health combines longitudinal survey data on respondents' social, economic, psychological, and physical well-being with contextual data on the family, neighborhood, community, school, friendships, peer groups, and romantic relationships. Add Health Wave I data collection took place between September 1994 and December 1995, and included both an in-school questionnaire and in-home interview. The in-school questionnaire was administered to more than 90,000 students in grades 7 through 12, and gathered information on social and demographic characteristics of adolescent respondents, education and occupation of parents, household structure, expectations for the future, self-esteem, health status, risk behaviors, friendships, and school-year extracurricular activities. All students listed on a sample school's roster were eligible for selection into the core in-home interview sample. In-home interviews included topics such as health status, health-facility utilization, nutrition, peer networks, decision-making processes, family composition and dynamics, educational aspirations and expectations, employment experience, romantic and sexual partnerships, substance use, and criminal activities. A parent, preferably the resident mother, of each adolescent respondent interviewed in Wave I was also asked to complete an interviewer-assisted questionnaire covering topics such as inheritable health conditions, marriages and marriage-like relationships, neighborhood characteristics, involvement in volunteer, civic, and school activities, health-affecting behaviors, education and employment, household income and economic assistance, parent-adolescent communication and interaction, parent's familiarity with the adolescent's friends and friends' parents. Add Health data collection recommenced for Wave II from April to August 1996, and included almost 15,000 follow-up in-home interviews with adolescents from Wave I. Interview questions were generally similar to Wave I, but also included questions about sun exposure and more detailed nutrition questions. Respondents were asked to report their height and weight during the course of the interview, and were also weighed and measured by the interviewer. From August 2001 to April 2002, Wave III data were collected through in-home interviews with 15,170 Wave I respondents (now 18 to 26 years old), as well as interviews with their partners. Respondents were administered survey questions designed to obtain information about family, relationships, sexual experiences, childbearing, and educational histories, labor force involvement, civic participation, religion and spirituality, mental health, health insurance, illness, delinquency and violence, gambling, substance abuse, and involvement with the criminal justice system. High School Transcript Release Forms were also collected at Wave III, and these data comprise the Education Data component of the Add Health study. Wave IV in-home interviews were conducted in 2008 and 2009 when the original Wave I respondents were 24 to 32 years old. Longitudinal survey data were collected on the social, economic, psychological, and health circumstances of respondents, as well as longitudinal geographic data. Survey questions were expanded on educational transitions, economic status and financial resources and strains, sleep patterns and sleep quality, eating habits and nutrition, illnesses and medications, physical activities, emotional content and quality of current or most recent romantic/cohabiting/marriage relationships, and maltreatment during childhood by caregivers. Dates and circumstances of key life events occurring in young adulthood were also recorded, including a complete marriage and cohabitation history, full pregnancy and fertility histories from both men and women, an educational history of dates of degrees and school attendance, contact with the criminal justice system, military service, and various employment events, including the date of first and current jobs, with respective information on occupation, industry, wages, hours, and benefits. Finally, physical measurements and biospecimens were also collected at Wave IV, and included anthropometric measures of weight, height and waist circumference, cardiovascular measures such as systolic blood pressure, diastolic blood pressure, and pulse, metabolic measures from dried blood spots assayed for lipids, glucose, and glycosylated hemoglobin (HbA1c), measures of inflammation and immune function, including High sensitivity C-reactive protein (hsCRP) and Epstein-Barr virus (EBV). Wave V data collection took place from 2016 to 2018, when the original Wave I respondents were 33 to 43 years old. For the first time, a mixed mode survey design was used. In addition, several experiments were embedded in early phases of the data collection to test response to various treatments. A similar range of data was collected on social, environmental, economic, behavioral, and health circumstances of respondents, with the addition of retrospective child health and socio-economic status questions. Physical measurements and biospecimens were again collected at Wave V, and included most of the same measures as at Wave IV. Datasets: DS0: Study-Level Files DS1: Wave I: In-Home Questionnaire, Public Use Sample DS2: Wave I: Public Use Contextual Database DS3: Wave I: Network Variables DS4: Wave I: Public Use Grand Sample Weights DS5: Wave II: In-Home Questionnaire, Public Use Sample DS6: Wave II: Public Use Contextual Database DS7: Wave II: Public Use Grand Sample Weights DS8: Wave III: In-Home Questionnaire, Public Use Sample DS9: Wave III: In-Home Questionnaire, Public Use Sample (Section 17: Relationships) DS10: Wave III: In-Home Questionnaire, Public Use Sample (Section 18: Pregnancies) DS11: Wave III: In-Home Questionnaire, Public Use Sample (Section 19: Relationships in Detail) DS12: Wave III: In-Home Questionnaire, Public Use Sample (Section 22: Completed Pregnancies) DS13: Wave III: In-Home Questionnaire, Public Use Sample (Section 23: Current Pregnancies) DS14: Wave III: In-Home Questionnaire, Public Use Sample (Section 24: Live Births) DS15: Wave III: In-Home Questionnaire, Public Use Sample (Section 25: Children and Parenting) DS16: Wave III: Public Use Education Data DS17: Wave III: Public Use Graduation Data DS18: Wave III: Public Use Education Data Weights DS19: Wave III: Add Health School Weights DS20: Wave III: Peabody Picture Vocabulary Test (PVT), Public Use DS21: Wave III: Public In-Home Weights DS22: Wave IV: In-Home Questionnaire, Public Use Sample DS23: Wave IV: In-Home Questionnaire, Public Use Sample (Section 16B: Relationships) DS24: Wave IV: In-Home Questionnaire, Public Use Sample (Section 16C: Relationships) DS25: Wave IV: In-Home Questionnaire, Public Use Sample (Section 18: Pregnancy Table) DS26: Wave IV: In-Home Questionnaire, Public Use Sample (Section 19: Live Births) DS27: Wave IV: In-Home Questionnaire, Public Use Sample (Section 20A: Children and Parenting) DS28: Wave IV: Biomarkers, Measures of Inflammation and Immune Function DS29: Wave IV: Biomarkers, Measures of Glucose Homeostasis DS30: Wave IV: Biomarkers, Lipids DS31: Wave IV: Public Use Weights DS32: Wave V: Mixed-Mode Survey, Public Use Sample DS33: Wave V: Mixed-Mode Survey, Public Use Sample (Section 16B: Pregnancy, Live Births, Children and Parenting) DS34: Wave V: Biomarkers, Anthropometrics DS35: Wave V: Biomarkers, Cardiovascular Measures DS36: Wave V: Biomarkers, Demographics DS37: Wave V: Biomarkers, Measures of Glucose Homeostasis DS38: Wave V: Biomarkers, Measures of Inflammation and Immune Function DS39: Wave V: Biomarkers, Lipids DS40: Wave V: Biomarkers, Medication Use DS41: Wave V: Biomarkers, Renal Function DS42: Wave V: Public Use Weights Wave I: The Stage 1 in-school sample was a stratified, random sample of all high schools in the United States. A school was eligible for the sample if it included an 11th grade and had a minimum enrollment of 30 students. A feeder school -- a school that sent graduates to the high school and that included a 7th grade -- was also recruited from the community. The in-school questionnaire was administered to more than 90,000 students in grades 7 through 12. The Stage 2 in-home sample of 27,000 adolescents consisted of a core sample from each community, plus selected special over samples. Eligibility for over samples was determined by an adolescent's responses on the in-school questionnaire. Adolescents could qualify for more than one sample. Wave II: The Wave II in-home interview surveyed almost 15,000 of the same students one year after Wave I. Wave III: The in-home Wave III sample consists of over 15,000 Wave I respondents who could be located and re-interviewed six years later. Wave IV: All original Wave I in-home respondents were eligible for in-home interviews at Wave IV. At Wave IV, the Add Health sample was dispersed across the nation with respondents living in all 50 states. Administrators were able to locate 92.5% of the Wave IV sample and interviewed 80.3% of eligible sample members. Wave V: All Wave I respondents who were still living were eligible at Wave V, yielding a pool of 19,828 persons. This pool was split into three stratified random samples for the purposes of survey design testing. For additional information on sampling, including detailed information on special oversamples, please see the Add Health Study Design page. audio computer-assisted self interview (ACASI); computer-assisted personal interview (CAPI); computer-assisted self interview (CASI); face-to-face interview; mixed mode; paper and pencil interview (PAPI); telephone interviewWave V data files were minimally processed by ICPSR. For value labeling, missing value designation, and question text (where applicable), please see the available P.I. Codebook/Questionnaires. The study-level documentation (Data Guide, User Guide) does not include Wave V datasets.Documentation for Waves prior to Wave V may use an older version of the study title.Users should be aware that version history notes dated prior to 2015-11-09 do not apply to the current organization of the datasets.Please note that dates present in the Summary and Time Period fields are taken from the Add Health Study Design page. The Date of Collection field represents the range of interview dates present in the data files for each wave.Wave I and Wave II field work was conducted by the National Opinion Research Center at the University of Chicago.Wave III, Wave IV, and Wave V field work was conducted by the Research Triangle Institute.For the most updated list of related publications, please see the Add Health Publications Web site.Additional information on the National Longitudinal Study of Adolescent to Adult Health (Add Health) series can be found on the Add Health Web site. Add Health was developed in response to a mandate from the U.S. Congress to fund a study of adolescent health. Waves I and II focused on the forces that may influence adolescents' health and risk behaviors, including personal traits, families, friendships, romantic relationships, peer groups, schools, neighborhoods, and communities. As participants aged into adulthood, the scientific goals of the study expanded and evolved. Wave III explored adolescent experiences and behaviors related to decisions, behavior, and health outcomes in the transition to adulthood. Wave IV expanded to examine developmental and health trajectories across the life course of adolescence into young adulthood, using an integrative study design which combined social, behavioral, and biomedical measures data collection. Wave V aimed to track the emergence of chronic disease as the cohort aged into their 30s and early 40s. Add health is a school-based longitudinal study of a nationally-representative sample of adolescents in grates 7-12 in the United States in 1945-45. Over more than 20 years of data collection, data have been collected from adolescents, their fellow students, school administrators, parents, siblings, friends, and romantic partners through multiple data collection components. In addition, existing databases with information about respondents' neighborhoods and communities have been merged with Add Health data, including variables on income poverty, unemployment, availability and utilization of health services, crime, church membership, and social programs and policies. The data files are not weighted. However, the collection features a number of weight variables contained within the following datasets: DS4: Wave I: Public Use Grand Sample Weights DS7: Wave II: Public Use Grand Sample Weights DS18: Wave III: Public Use Education Data Weights DS19: Wave III: Add Health School Weights DS21: Wave III: Public In-Home Weights DS31: Wave IV: Public Use Weights DS42: Wave V: Public Use Weights Please note that these weights files do not apply to the Biomarker data files. For additional information on the application of weights for data analysis, please see the ICPSR User Guide, or the Guidelines for Analyzing Add Health Data. Response Rates: Response rates for each wave were as follows: Wave I: 79 percent Wave II: 88.6 percent Wave III: 77.4 percent Wave IV: 80.3 percent Wave V: 71.8 percent Adolescents in grades 7 through 12 during the 1994-1995 school year. Respondents were geographically located in the United States.

Supplemental material, Supplementary_Figure_5 for Comparing CST Lesion Metrics as Biomarkers for Recovery of Motor and Proprioceptive Impairments After Stroke by Sonja E. Findlater, Rachel L. Hawe, Erin L. Mazerolle, Abdulaziz S. Al Sultan, Jessica M. Cassidy, Stephen H. Scott, G. Bruce Pike and Sean P. Dukelow in Neurorehabilitation and Neural Repair

Gender distribution by population size group. (XLSX 16 kb)

Supplemental material, Supplementary_Figure_3 for Comparing CST Lesion Metrics as Biomarkers for Recovery of Motor and Proprioceptive Impairments After Stroke by Sonja E. Findlater, Rachel L. Hawe, Erin L. Mazerolle, Abdulaziz S. Al Sultan, Jessica M. Cassidy, Stephen H. Scott, G. Bruce Pike and Sean P. Dukelow in Neurorehabilitation and Neural Repair

The most recent series of data collection waves for NHANES began in 1999. Every year, approximately 7,000 individuals, of all ages, are interviewed in their homes and of these, approximately 5,000 complete the health examination component of the survey. A majority of the health examinations are conducted in mobile examination centers (MECs). The MECs provide an ideal setting for the collection of high quality data in a standardized environment. In addition to the MEC examinations, a small number of survey participants receive an abbreviated health examination in their homes if they are unable to come to the MEC. The NHANES target population is the civilian, noninstitutionalized United States population. NHANES 2001-2002 includes over-sampling of low-income persons, adolescents 12-19 years of age, persons 60 years of age and older, African Americans, and Mexican Americans. Initially, households are identified for inclusion in the NHANES sample and an advance letter is mailed to each address informing the occupant(s) that an NHANES interviewer will visit their home. The household interview component is comprised of Screener, Sample Person, and Family interviews, each of which has a separate questionnaire (please refer to the data file documentation). Trained household interviewers administer all of the questionnaires. In most cases, the interview setting was the survey participant's home. The interview data are recorded using the Blaise computer-assisted personal interview (CAPI) system. When the interviewer arrives at the home, he or she shows an official identification badge and briefly explains the purpose of the survey. If the occupant has not seen the advance letter, a copy is given to them to read. The interviewer requests that the occupant answer a brief questionnaire to determine if any household occupants are eligible to participate in NHANES. If eligible individuals are identified, the interviewer proceeds with efforts to recruit these individuals. Initially, the interviewer explains the household questionnaires to all eligible participants 16 years of age and older, informs the potential respondents of their rights, and provides assurances about the confidentiality of the survey data (reiterating what is stated in the advance letter). A majority of the household interviews are conducted during the first contact. If this is inconvenient for the survey participant, an appointment is made to administer the household interview questionnaires later. Household interviews for survey participants under 16 years of age are conducted with a proxy (usually their parent or guardian). If there is no one living in the household who is over 16, participants under 16 years of age are permitted to self-report. Respondents are asked to sign an Interview Consent Form agreeing to participate in the household interview portion of the survey. For participants 16-17 years of age a parent or guardian consents and the child gives his/her assent. After the household interview is completed, the interviewer reviews a second informed consent brochure with the participant. This brochure contains detailed information about the NHANES health examination component. All interviewed persons are asked to complete the health examination component. Those who agree to participate are asked to sign additional consent forms for the health examination component. The interviewer telephones the NHANES field office from the participant's home to schedule an appointment for the examination. The interviewer informs the participants that they will receive remuneration as well as reimbursement for transportation and childcare expenses, if necessary. Target Populations There are different target population groups for the topics within and between NHANES questionnaire sections. For example, in the Nutrition and Diet Behavior section, questions pertaining to infant nutrition and breast-feeding were asked of proxy respondents for children 6 years of age and younger, alcohol consumption frequency questions were asked of persons 20 years of age and older, and senior meal program participation questions were asked of respondents 60 years of age and older. Data users should review the survey questionnaire codebooks thoroughly to determine the target populations for each NHANES questionnaire section and sub-section. The NHANES Health Examination Component When a participant arrives at the MEC, the MEC Coordinator greets the participant and verifies all pertinent identifier information. The participant is given a disposable paper gown, a pair of slippers, and a urine specimen cup. MEC staff direct survey participants to the rooms where the examination components are conducted. Each MEC survey team consists of one physician, one dentist, two dietary interviewers, three certified medical technologists, five health technicians, one phlebotomist, two interviewers, and one computer data manager. Additionally, there is a person designated as the Coordinator who is responsible for managing the movement of participants between examinations, providing remuneration, and distributing a preliminary report of findings. Upon completion of the examination, each examinee is remunerated. Some of the medical findings of the examination are given to the examinees before they leave the MEC. The other reportable survey findings are mailed to participants after the laboratory assays and special tests are completed. MEC Operations Three MECs are equipped for use in NHANES. Each MEC consists of four large, inter-connected trailer units. An advance team sets up the MECs prior to the start of the survey examinations. Water, sewer, electrical, and communication lines are connected during set-up. The MEC equipment and data collection systems must be checked and calibrated prior to the start of survey data collection. The MECs are open a total of five days per week, and the nonoperational days change on a rotating basis so that appointments can be scheduled on any day of the week. Two examination sessions are conducted daily. For the convenience of the survey participants, appointments can be scheduled during morning, afternoon, or evening hours. The examinations require up to three hours to complete. At any given time during the survey, examinations are conducted at two survey locations simultaneously. Staff vacations are scheduled for periods of about one month at New Years and about two weeks during the summer, leaving ten and one-half months to conduct examinations. Second Day Examinations and Dietary Interviews Second day (i.e., repeat) MEC examinations were pilot tested in 1999 and implemented in 2000. Approximately 5 percent of examined persons over 20 years of age from each survey location were asked to complete second day exams. Second day dietary interviews were completed on ten percent of all examined persons in 2000. The second day dietary interview is a primary data collection technique to improve the estimation of distributions of nutrient intakes. Second day examination and dietary data are not included in this data file. Home Examinations Participants under 1 year of age or 60 years of age and older, who are unable or unwilling to come to the MEC for an examination, are eligible to receive a home examination. Home examination data are not included in this data file. Datasets: DS0: Study-Level Files DS1: Demographics DS11: Examination: Audiometry (Subsample) DS12: Examination: Audiometry Tympanometry DS13: Examination: Balance (Subsample) DS14: Examination: Bioelectrical Impedance Analysis DS15: Examination: Body Measurements DS16: Examination: Blood Pressure DS17: Examination: Cardiovascular Fitness DS18: Examination: Composite International Diagnostic Interview (Generalized Anxiety Disorder) (Subsample) DS19: Examination: Composite International Diagnostic Interview (Major Depression Module) (Subsample) DS20: Examination: Composite International Diagnostic Interview (Panic Disorder Module) (Subsample) DS21: Examination: Dietary Interview (Individual Foods File) DS22: Examination: Dietary Interview (Total Nutrients) DS23: Examination: Dual Energy X-ray Absorptiometry (DXX) DS24: Examination: Dual Energy X-ray Absorptiometry (DXX) -- Subset DS25: Examination: Lower Extremity Disease (Ankle Brachial Blood Pressure Index) DS26: Examination: Lower Extremity Disease (Peripheral Neuropathy) DS27: Examination: Muscle Strength DS28: Examination: Oral Health (Dentition) DS29: Examination: Oral Health Periodontal-Lower DS30: Examination: Oral Health Periodontal-Upper DS31: Examination: Oral Health (Referral) DS32: Examination: Vision Exam DS100: Laboratory: Surplus Sera Cystatin C DS101: Laboratory: Antibody to Cytomegalovirus IgG (Surplus Sera) DS102: Laboratory: Antibody to Human Herpes Virus 1 (Ages 6-13) (Surplus Sera) DS103: Laboratory: Antibody to Mumps (Surplus Sera) DS104: Laboratory: Nitrate Thiocyanate Perchlorate (Surplus Urine) DS105: Laboratory: Polyfluoroalkyl Chemicals (Pooled Samples) DS106: Laboratory: Serum Transferrin and Receptor DS107: Laboratory: Unmetabolized Folic Acid (Surplus Sera) DS108: Laboratory: Varicella-Zoster Virus Antibody (Surplus Sera) DS109: Laboratory: Phlebotomy DS110: Laboratory: PHPYPA Urinary Phthalates (Subsample) DS111: Laboratory: Urine Collection (Pregnancy) DS112: Laboratory: Lab 02 Hepatitis DS113: Laboratory: Lab 02 Hepatitis B Surface Antibody DS114: Laboratory: Lab 02 Hepatitis A Antibody DS115: Laboratory: Lab 03 Human Immunodeficiency Virus DS116: Laboratory: Lab 04 Volatile Organic Compounds in Blood and Water DS117: Laboratory: Lab 05 Chlamydia and Gonorrhea DS118: Laboratory: Lab 06 Nutritional Biochemistries DS119: Laboratory: Lab 06 Vitamins A, E, and Carotenoids DS120: Laboratory: Lab 06 Vitamin D DS121: Laboratory: Lab 06 Urinary Iodine (Subsample) DS122: Laboratory: Lab 06HM Heavy Metals (Subsample) DS123: Laboratory: Lab 09 Herpes I and Herpes II DS124: Laboratory: Lab 10 Glycohemoglobin DS125: Laboratory: Lab 10AM Plasma Glucose (Subsample) DS126: Laboratory: Lab 11 C-Reactive Protein DS127: Laboratory: Lab 11 PSA DS128: Laboratory: Lab 13 Total Cholesterol and HDL Cholesterol DS129: Laboratory: Lab 13AM Triglycerides (Subsample) DS130: Laboratory: Lab 16 Urinary Albumin and Creatinine DS131: Laboratory: Lab 17 Toxoplasma (IgG IgM Dye Differential Agglutination and Avidity) DS132: Laboratory: Lab 19 Measles Rubella and Varicella DS133: Laboratory: Lab 20 Lead Dust DS134: Laboratory: Lab 25 Complete Blood Count DS135: Laboratory: Lab 26 Pesticides (Subsample) DS136: Laboratory: Lab 28 Dioxins (Subsample) DS137: Laboratory: Lab 34 Trichomonos Vaginalis and Bacterial Vaginosis DS138: Laboratory: Lab 35 Methicillin Resistant Staphylococcus Aureus DS139: Laboratory: Lab 36 Syphilis and Treponema Pallidum DS140: Laboratory: Lab 39 Erythrocyte Protoporphyrin DS141: Laboratory: Lab 40 Biochemistry Profile and Hormones DS142: Laboratory: Lab 40T4 Thyroid Stimulating Hormone and Thryoxine (Subsample) DS143: Laboratory: Lab 40 Iron and TIBC DS144: Laboratory: Lab 06 Second Day DS145: Laboratory: Lab 06 Vitamin D Second Day DS146: Laboratory: Lab 40 Second Day Standard Biochemistry Profile Follicle Stimulating Hormone and Luteinizing Hormone DS201: Questionnaire: Acculturation DS202: Questionnaire: Alcohol Use DS203: Questionnaire: Analgesics Pain Relievers DS204: Questionnaire: Audiometry DS205: Questionnaire: Balance DS206: Questionnaire: Blood Pressure DS207: Questionnaire: Cardiovascular Disease and Health DS208: Questionnaire: Cognitive Functioning DS209: Questionnaire: Current Health Status DS210: Questionnaire: Dermatology DS211: Questionnaire: Diabetes DS212: Questionnaire: Diet Behavior and Nutrition DS213: Questionnaire: Dietary Supplement Use -- Supplement Counts DS214: Questionnaire: Dietary Supplement Use -- Participants Use of Supplement DS215: Questionnaire: Dietary Supplement Use -- Supplement Information DS216: Questionnaire: Dietary Supplement Use -- Ingredient Information DS217: Questionnaire: Dietary Supplement Use -- Supplement Blend DS218: Questionnaire: Drug Use DS219: Questionnaire: Early Childhood DS220: Questionnaire: Family Smoking DS221: Questionnaire: Food Security DS222: Questionnaire: Health Insurance DS223: Questionnaire: Hepatitis C Follow-Up Questionnaire DS224: Questionnaire: Hospital Utilization DS225: Questionnaire: Housing Characteristics DS226: Questionnaire: Immunization DS227: Questionnaire: Medical Conditions DS228: Questionnaire: Miscellaneous Pain DS229: Questionnaire: Occupation DS230: Questionnaire: Oral Health DS231: Questionnaire: Osteoporosis DS232: Questionnaire: Pesticide Use DS233: Questionnaire: Physical Activity DS234: Questionnaire: Physical Activity Individual Activities File DS235: Questionnaire: Physical Functioning DS236: Questionnaire: Prescription Medications DS237: Questionnaire: Drug Information DS238: Questionnaire: Prostate Conditions DS239: Questionnaire: Reproductive Health DS240: Questionnaire: Respiratory Health and Disease DS241: Questionnaire: Sexual Behavior DS242: Questionnaire: Social Support DS243: Questionnaire: Smoking and Tobacco Use DS244: Questionnaire: Smoking and Tobacco Use (MEC) DS245: Questionnaire: Urology and Kidney Conditions DS246: Questionnaire: Vision DS247: Questionnaire: Weight History Sample weights are available for analyzing NHANES 2001-2002 data. Most data analyses require either the interviewed sample weight (variable name: WTINT2YR) or examined sample weight (variable name: WTMEC2YR). The two-year sample weights (WTINT2YR, WTMEC2YR) should be used for NHANES 2001-2002 analyses and the four-year sample weights (WTINT4YR, WTMEC4YR) for combined analyses of NHANES 1999-2000 and NHANES 2001-2002 data. Use of the correct sample weight for NHANES analyses is extremely important and depends on the variables being used. A good rule of thumb is to use "the least common denominator" approach. With this approach, the analyst checks the variables of interest. The variable that was collected on the smallest number of persons is the least common denominator, and the sample weight that applies to that variable is the appropriate one to use for that particular analysis. Please refer to the NHANES 2001-2002 analytic guidelines provided with the data release files to determine the appropriate analytic methodology. NCHS June 2004 Version--NHANES Analytic Guidelines Beginning in 1999, the National Health and Nutrition Examination Survey (NHANES) became a continuous, annual survey rather than the periodic survey that it had been in the past. For a variety of reasons, including disclosure and reliability issues, the survey data are released on public use data files every two years. Thus, the data release cycle for the ongoing (and continuous) NHANES is described as NHANES 1999-2000, NHANES 2001-2002, NHANES 2003-2004, etc. In addition to the analysis of data from any two-year cycle, it is possible to combine two or more "cycles" (e.g., 1999-2000 and 2001-2002) to create NHANES 1999-2002, thus increasing sample size and analytic options. In order to produce estimates with greater statistical reliability, combining two or more two-year cycles of the continuous NHANES is encouraged and strongly recommended. To facilitate analysis of these first two cycles of the continuous NHANES, the appropriate four-year sample weights have been calculated and added to the demographic data files for both 1999-2000 and 2001-2002. Thus, users of the earlier release of the NHANES 1999-2000 demographic file must use the updated demographic file to appropriately analyze the combined four-year data. These four-year sample weights have the same variable name in each two-year demographic file. For example, for the sample persons for whom there are MEC data items, the variable name for the four year weight is WTMEC4YR. The procedure for variance estimation (sampling errors) was changed beginning with NHANES 1999-2000 to one that protects confidentiality and allows the use of "PSUs" and is the recommended approach for analysis on the ongoing and continuous NHANES. This method creates Masked Variance Units (MVUs) which can be used as if they were Pseudo PSUs to estimate sampling errors (similar to past NHANES). The Pseudo-PSUs on the data file are not the "true" design PSUs. They are a collection of secondary sampling units aggregated into groups called Masked Variance Units (MVUs) for the purpose of variance estimation. They produce variance estimates that closely approximate the variances that would have been estimated using the "true" design variance estimates. These MVUs have been created for both NHANES 1999-2000 and NHANES 2001-2002 and added to the demographic data files for both two-year periods. They can also be used for the combined four-year dataset. The stratum variable is SDMVSTRA and the PSU variable is SDMVPSU. Software such as SUDAAN, STATA, and SAS can be used to estimate sampling errors by the Taylor series (linearization) method. Typically, the dataset should first be sorted by SDMVSTRA and SDMVPSU. There are no replicate weights provided for NHANES 2001-2002. Replication techniques can still be used to estimate sampling errors if the software, such as WESVAR, computes its own set of replicate weights based on the nested PSU within stratum design. Some data components of NHANES are only available for 1999-2000 or 2001-2002. For these components, the two-year sample weights and the two-year MVUs can be used for analysis. For 2001-2002, the two-year weights and MVUs are provided on the demographic data file. For 1999-2000, the previously released demographic file has been updated to add the MVUs and four-year sample weights. At this time, the preferred approach for calculating sampling errors is to use the MVUs and to ignore the JK-1 technique utilized as an interim approach with the release of the NHANES 1999-2000 data. On occasion, there may be a particular issue that requires comparison of results from NHANES 1999-2000 with NHANES 2001-2002. For summary statistics such as means and proportions, the appropriate two-year sample weights and MVUs can be used for reasonably valid inferences (although caution should be used when producing estimates for any detailed population subgroup). Calculation of totals (e.g., estimates of the number of persons with a particular characteristic such as BMI greater than 30 or with impaired glucose tolerance) is not appropriate for NHANES 1999-2000 unless the numbers are ratio-adjusted to population counts based on year 2000 Census figures. This is not an issue for NHANES 2001-2002 which was linked to the 2000 Census counts. Users are encouraged to check the NHANES Web site on a regular basis to be aware of the latest version of these NHANES analytic guidelines. The National Health and Nutrition Examination Surveys (NHANES) is a program of studies designed to assess the health and nutritional status of adults and children in the United States. The NHANES combines personal interviews and physical examinations, which focus on different population groups or health topics. These surveys have been conducted by the National Center for Health Statistics (NCHS) on a periodic basis from 1971 to 1994. In 1999 the NHANES became a continuous program with a changing focus on a variety of health and nutrition measurements which were designed to meet current and emerging concerns. The surveys examine a nationally representative sample of approximately 5,000 persons each year. These persons are located in counties across the United States, 15 of which are visited each year. The 2001-2002 NHANES contains data for 11,039 individuals (and MEC examined sample size of 10,477) of all ages. Many questions that were asked in NHANES II, 1976-1980, Hispanic HANES 1982-1984, and NHANES III, 1988-1994, were combined with new questions in the NHANES 2001-2002. As in past health examination surveys, data were collected on the prevalence of chronic conditions in the population. Estimates for previously undiagnosed conditions, as well as those known to and reported by survey respondents, are produced through the survey. Risk factors, those aspects of a person's lifestyle, constitution, heredity, or environment that may increase the chances of developing a certain disease or condition, were examined. Data on smoking, alcohol consumption, sexual practices, drug use, physical fitness and activity, weight, and dietary intake were collected. Information on certain aspects of reproductive health, such as use of oral contraceptives and breastfeeding practices, were also collected. The diseases, medical conditions, and health indicators that were studied include: anemia, cardiovascular disease, diabetes and lower extremity disease, environmental exposures, equilibrium, hearing loss, infectious diseases and immunization, kidney disease, mental health and cognitive functioning, nutrition, obesity, oral health, osteoporosis, physical fitness and physical functioning, reproductive history and sexual behavior, respiratory disease (asthma, chronic bronchitis, emphysema), sexually transmitted diseases, skin diseases, and vision. The sample for the survey was selected to represent the United States population of all ages. Special emphasis in the 2001-2002 NHANES was on adolescent health and the health of older Americans. To produce reliable statistics for these groups, adolescents aged 15-19 years and persons aged 60 years and older were over-sampled for the survey. African Americans and Mexican Americans were also over-sampled to enable accurate estimates for these groups. Several important areas in adolescent health, including nutrition and fitness and other aspects of growth and development, were addressed. Since the United States has experienced dramatic growth in the number of older people during the twentieth century, the aging population has major implications for health care needs, public policy, and research priorities. NCHS is working with public health agencies to increase the knowledge of the health status of older Americans. NHANES has a primary role in this endeavor. In the examination, all participants visit the physician who takes their pulse or blood pressure. Dietary interviews and body measurements are included for everyone. All but the very young have a blood sample taken and see the dentist. Depending upon the age of the participant, the rest of the examination includes tests and procedures to assess the various aspects of health listed above. Usually, the older the individual, the more extensive the examination. Some persons who are unable to come to the examination center may be given a less extensive examination in their homes. Demographic data file variables are grouped into three broad categories: (1) Status Variables: provide core information on the survey participant. Examples of the core variables include interview status, examination status, and sequence number. (Sequence number is a unique ID assigned to each sample person and is required to match the information on this demographic file to the rest of the NHANES 2001-2002 data). (2) Recoded Demographic Variables: these variables include age (age in months for persons through age 19 years, 11 months; age in years for 1-84 year olds, and a top-coded age group of 85 years of age and older), gender, a race/ethnicity variable, current or highest grade of education completed, (less than high school, high school, and more than high school education), country of birth (United States, Mexico, or other foreign born), Poverty Income Ratio (PIR), income, and a pregnancy status variable (adjudicated from various pregnancy related variables). Some of the groupings were made due to limited sample sizes for the two-year data set. (3) Interview and Examination Sample Weight Variables: sample weights are available for analyzing NHANES 2001-2002 data. For a complete listing of survey contents for all years of the NHANES see the document -- Survey Content -- NHANES 1999-2010. audio computer-assisted self interview (ACASI), computer-assisted personal interview (CAPI), computer-assisted self interview (CASI), face-to-face interview, on-site questionnaire NCHS provides continuous updates/new data notification, as well as other important information for the NHANES. It is recommended that users of these data sign up for the information through the NHANES Listserv. The "What's New" page on the NHANES Web site provides updates/new information which may not be included in the listserv emails. Further, not all documentation files are included with this ICPSR release and may be found at the NHANES 2001-2002 Web site. In preparing the data files for this collection, the National Center for Health Statistics (NCHS) has removed direct identifiers and characteristics that might lead to identification of data subjects. As an additional precaution NCHS requires, under Section 308(d) of the Public Health Service Act (42 U.S.C. 242m), that data collected by NCHS not be used for any purpose other than statistical analysis and reporting. NCHS further requires that analysts not use the data to learn the identity of any persons or establishments and that the director of NCHS be notified if any identities are inadvertently discovered. ICPSR member institutions and other users ordering data from ICPSR are expected to adhere to these restrictions. Many variables that are listed in the Demographic questionnaire sections of the Household Interview were omitted (by NCHS) from this data release due to concerns about participant confidentiality. NCHS did not include confidential and administrative data in this release and further, some variables have been recoded or top-coded to protect the confidentiality of survey participants. Many of the NHANES 2001-2002 questions were also asked in NHANES II, 1976-1980, Hispanic HANES 1982-1984, and NHANES III, 1988-1994. New questions were added to the survey based on recommendations from survey collaborators, NCHS staff, and other interagency work groups. NHANES 2001-2002 survey design and demographic variables are found in Part 1 Demographics file in this release. All of the data files can be linked by using the common survey participant identification number (variable name: SEQN). Merging information from multiple NHANES 2001-2002 data files using SEQN ensures that the appropriate information for each survey participant is linked correctly. All data files should be sorted by SEQN. The NHANES 2001-2002 data files do not have the same number of records in each file. For example, there are different numbers of subjects in the Interview and Examination samples of the survey. Additionally, the number of records in each data file varies depending on gender and age profiles for the specific component(s). The sample person demographic file is composed of a limited set of core variables that are required to analyze NHANES 2001-2002 data. Per agreement with NCHS, ICPSR distributes the data file(s) and text of the technical documentation for this collection as prepared by NCHS. All data files have been merged with the demographics file with the exception of those parts that did not contain the linking variable SEQN which are as follows: Questionnaire: Dietary Supplement Use -- Supplement Information (Part 215), Questionnaire: Dietary Supplement Use -- Ingredient Information (Part 216), Questionnaire: Dietary Supplement Use -- Supplement Blend (Part 217), and Questionnaire: Drug Information (Part 237). The user guides that are presently available are comprised of documentation from the NCHS. These user guides do not reflect the merging of each file with the demographics file, as this was done by ICPSR staff. Part 13 Balance (Subsample) and part 14 Examination: Bioelectrical Impedance Analysis have been updated to correct an error in the data files. The NHANES survey design is a stratified, multistage probability sample of the civilian noninstitutionalized United States population. The stages of sample selection are: (1) selection of Primary Sampling Units (PSUs) which are counties or small groups of contiguous counties, (2) segments within PSUs (a block or group of blocks containing a cluster of households), (3) households within segments, and (4) one or more participants within households. A total of 15 PSUs are visited during a 12-month time period. Details of the design and content of each survey are available at the NHANES Web site. ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major statistical software formats as well as standard codebooks to accompany the data. In addition to these procedures, ICPSR performed the following processing steps for this data collection: Performed consistency checks.; Created variable labels and/or value labels.; Standardized missing values.; Checked for undocumented or out-of-range codes.. The NHANES target population is the civilian, noninstitutionalized United States population. National Health and Nutrition Examination Survey (NHANES) and Followup Series Presence of Common Scales: DISC -- Predictive Scale