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The Americans' Changing Lives (ACL) survey series is an ongoing, nationally representative, longitudinal study focusing especially on differences between Black and White Americans in middle and late life. These data constitute the first, second, third, fourth, fifth, and sixth waves in a panel survey covering a wide range of sociological, psychological, mental, and physical health items. Wave I of the study began in 1986 with a nation face-to-face survey of 3,617 adults ages 25 and up, with Black Americans and people aged 60 and over over-sampled at twice the rate of the others. Wave II constitutes face-to-face re-interviews in 1989 of those still alive. Survivors have been re-interviewed by telephone, and when necessary face-to-face, in 1994 (Wave III), 2001/02 (Wave IV), 2011 (Wave V), and 2019/21 (Wave VI).

Please note that for Wave VI, the majority of data collection occurred in 2019, with only a small subset (n=39) of participants surveyed in 2021.

ACL was designed and sought to investigate the following: (1) The ways in which a wide range of activities and social relationships that people engage in are broadly "productive," (2) how individuals adapt to acute life events and chronic stresses that threaten the maintenance of health, effective functioning, and productive activity, and (3) sociocultural variations in the nature, meaning, determinants, and consequences of productive activity and relationships. Among the topics covered are interpersonal relationships (spouse/partner, children, parents, friends), sources and levels of satisfaction, social interactions and leisure activities, traumatic life events (physical assault, serious illness, divorce, death of a loved one, financial or legal problems), perceptions of retirement, health behaviors (smoking, alcohol consumption, overweight, rest), and utilization of health care services (doctor visits, hospitalization, nursing home institutionalization, bed days). Also included are measures of physical health, psychological well-being, and indices referring to cognitive functioning.

Demographic information provided for individuals includes household composition, number of children and grandchildren, employment status, occupation and work history, income, family financial situation, religious beliefs and practices, ethnicity, race, education, sex, and region of residence.

The Midlife in the United States (MIDUS) is a collaborative, interdisciplinary investigation of patterns, predictors, and consequences of midlife development in the areas of physical health, psychological well-being, and social responsibility. A description of the study and findings from it are available at http://www.midus.wisc.edu.

The first wave of the MIDUS study (MIDUS 1 or M1) collected survey data from a total of 7,108 participants. The baseline sample was comprised of individuals from four subsamples: (1) a national RDD (random digit dialing) sample (n=3,487); (2) oversamples from five metropolitan areas in the U.S. (n=757); (3) siblings of individuals from the RDD sample (n=950); and (4) a national RDD sample of twin pairs (n=1,914). All eligible participants were non-institutionalized, English-speaking adults in the coterminous United States, aged 25 to 74.

Data from the samples were collected primarily in 1995/96. The survey (Project 1) dataset contains responses from a 30-minute Phone interview and two 50-page Self-Administered Questionnaire (SAQ) instruments. Of the 7,108 respondents who completed the Phone interview, 6,325 also completed the SAQ.

This updated version of the study is comprised of three primary datasets:

Dataset 1, Main, Siblings, and Twin Data, contains responses from the main survey of 7,108 respondents. Respondents were asked to provide extensive information on their physical and mental health throughout their adult lives, and to assess the ways in which their lifestyles, including relationships and work-related demands, contributed to the conditions experienced. Those queried were asked to describe their histories of physical ailments, including heart-related conditions and cancer, as well as the treatment and/or lifestyle changes they went through as a result. A series of questions addressed alcohol, tobacco, and illegal drug use, and focused on history of use, regularity of use, attempts to quit, and how the use of those substances affected respondents' physical and mental well-being. Additional questions addressed respondents' sense of control over their health, their awareness of changes in their medical conditions, commitment to regular exercise and a healthy diet, experience with menopause, the decision-making process used to deal with health concerns, experiences with nontraditional remedies or therapies, and history of attending support groups. Respondents were asked to compare their overall well-being with that of their peers and to describe social, physical, and emotional characteristics typical of adults in their 20's, 40's, and 60's. Information on the work histories of respondents and their significant others was also elicited, with items covering the nature of their occupations, work-related physical and emotional demands, and how their personal health had correlated to their jobs. An additional series of questions focusing on childhood queried respondents regarding the presence/absence of their parents, religion, rules/punishments, love/affection, physical/verbal abuse, and the quality of their relationships with their parents and siblings. Respondents were also asked to consider their personal feelings of accomplishment, desire to learn, sense of control over their lives, interests, and hopes for the future.

The Datasets previously numbered 2 and 3 have been removed to avoid redundancies, and all datasets have been renumbered. Please refer to the readme file.

Dataset 2, Twin Screener Data, provides the first national sample of twin pairs ascertained randomly via the telephone.

Dataset 3, Coded Text Responses, describes how open-ended textual responses in the MIDUS 1 Computer-Assisted Telephone Interview (CATI) and Self-Administered Questionnaire (SAQ) were transformed into categorical numeric codes. These codes are included in a stand-alone dataset containing only those cases (N=3,950) that contained text data in their responses.

Online Analysis Only: Datasets 1, 2, and 3 were merged together by the SU_ID variable to form "Merged Data with Weights (Online Analysis Only)" (Dataset 4) for online analysis capabilities.

MIDUS also maintains a Colectica portal, which allows users to interact with variables across waves and create customized subsets. Registration is required.

In 1995-1996, the MacArthur Midlife Research Network carried out a national survey of 7,108 Americans aged 25 to 74 (MIDLIFE IN THE UNITED STATES (MIDUS), 1995-1996 [ICPSR 2760]). The purpose of the study was to investigate the role of behavioral, psychological, and social factors in understanding age-related differences in physical and mental health. The study was innovative for its broad scientific scope, its diverse samples (which included twins and the siblings of main sample respondents), and its creative use of in-depth assessments in key areas (e.g., daily stress and cognitive functioning). A description of the study and findings from it are available at http://www.midus.wisc.edu. With support from the National Institute on Aging, a longitudinal follow-up of the original MIDUS samples: core sample (N = 3,487), metropolitan over-samples (N = 757), twins (N = 925 complete pairs), and siblings (N = 950), was conducted in 2004-2006. Guiding hypotheses for it, at the most general level, were that behavioral and psychosocial factors are consequential for physical and mental health. MIDUS 2 respondents were aged 35 to 86. Data collection largely repeated baseline assessments (e.g., phone interview and extensive self-administered questionnaire), with additional questions in selected areas (e.g., cognitive functioning, optimism and coping, stressful life events, and caregiving). To add refinements to MIDUS 2, an African American sample (N = 592) was recruited from Milwaukee, Wisconsin, who participated in a personal interview and completed a questionnaire paralleling the above assessments. Survey data for the Milwaukee sample are available in a separate project [ICPSR 22840]. Also administered was a modified form of the mail questionnaire, via telephone, to respondents who did not complete a self-administered questionnaire.

In 1995-1996, the MacArthur Midlife Research Network carried out a national survey of over 7,000 Americans aged 25 to 74 [ICPSR 2760]. The purpose of the study was to investigate the role of behavioral, psychological, and social factors in understanding age-related differences in physical and mental health. The study was innovative for its broad scientific scope, its diverse samples (which included siblings of the main sample respondents and a national sample of twin pairs), and its creative use of in-depth assessments in key areas (e.g. daily diary of stressful experiences [ICPSR 3725] and cognitive functioning [ICPSR 3596]) on a subset of participants. A detailed description of the study and findings generated by it are available at: http://www.midus.wisc.edu

With support from the National Institute on Aging, a follow-up of the original Midlife Development in the United States (MIDUS) sample was conducted in 2004 (MIDUS 2 [ICPSR 4652]). The daily stress and cognitive functioning projects were repeated and expanded at MIDUS 2; in addition the protocol was expanded to include biomarkers and neuroscience.

In 2013 a third wave (MIDUS 3) of survey data was collected on longitudinal participants. Data collection for this follow-up wave largely repeated baseline assessments (e.g., phone interview and extensive self-administered questionnaire), with additional questions in selected areas such as economic recession experiences. Cognitive functioning data were also collected at the same time, while data collection for the daily diary, biomarker, and neuroscience projects commenced in 2017.

MIDUS also maintains a Colectica portal, which allows users to interact with variables across waves and create customized subsets. Registration is required.

In 2011-2014, the MIDUS Refresher study recruited a national probability sample of 3,577 adults, aged 25 to 74, designed to replenish the original MIDUS 1 baseline cohort and paralleling the five decadal age groups of the MIDUS 1 baseline survey [ICPSR 2760]. The MIDUS Refresher survey employed the same comprehensive assessments as those assembled on the existing MIDUS sample, but with additional questions about the effect of the economic recession of 2008-09.

The MIDUS Refresher collection is split into two datasets: Aggregate Data and Coded Text Data. The Coded Text Dataset provides coded responses to open-ended question items in the Aggregate Dataset. The survey data collection (Project 1) [MIDUS, ICPSR 2760] consisted of a 30-minute phone interview followed by two 50-page mailed self-administered questionnaires. Survey data were collected on demographic, psycho-social, and physical and mental health information. This new crosssectional MIDUS sample allows the examination of period effects on health (mental and physical) related to the economic recession by comparing the pre-recession MIDUS 1 sample with the post-recession MIDUS Refresher sample. A further objective of the MIDUS Refresher sample was to strengthen cross-project analyses in MIDUS by increasing the sample sizes available for testing hypotheses dealing with the interplay of key factors (e.g., socioeconomic status, gender, psychosocial factors, biological factors) in mid- and laterlife health. To that end, the MIDUS Refresher sample followed the same multi-disciplinary protocol established in the main MIDUS sample, in that after completing the survey protocol respondents were asked to complete a cognitive assessment by phone (Project 3) [MIDUS 3, ICPSR 36346] and later became eligible to participate in daily diary assessments (Project 2) [MIDUS 2, ICPSR 4652] biomarker assessments (Project 4) [MIDUS 2: Biomarker Project, ICPSR 29282] and neuroscience assessments (Project 5) [MIDUS 2: Neuroscience Project, ICPSR 28683].

The MIDUS Refresher was funded by the National Institute on Aging as two separate but related efforts: The MIDUS Refresher younger decades (MRY), was fielded in November, 2011, and recruited over 2,100 new participants aged 25 to 54; Funding was later added for the MIDUS Refresher older decades (MRO), which was fielded in June, 2013 and recruited over 1,400 new participants aged 55 to 74.

Demographic variables include age, sex, gender, race, religion, and marital status.

The National Social Life, Health and Aging Project (NSHAP) is the first population-based study of health and social factors on a national scale, aiming to understand the well-being of older, community-dwelling Americans by examining the interactions among physical health, illness, medication use, cognitive function, emotional health, sensory function, health behaviors, and social connectedness. It is designed to provide health providers, policy makers, and individuals with useful information and insights into these factors, particularly on social and intimate relationships. The National Opinion Research Center (NORC), along with Principal Investigators at the University of Chicago, conducted more than 3,000 interviews during 2005 and 2006 with a nationally representative sample of adults aged 57 to 85. Face-to-face interviews and biomeasure collection took place in respondents' homes. The following files constitute Round 1: Core Data, Marital/Cohabiting History Data, Social Networks Data, Medications Data, and Sexual Partners Data.

Included in the Core file (Datasets 1 and 2) are demographic characteristics, such as gender, age, education, race, and ethnicity. Other topics covered respondents' social networks, social and cultural activity, physical and mental health including cognition, well-being, illness, medications and alternative therapies, history of sexual and intimate partnerships and patient-physician communication, in addition to bereavement items. In addition data was collected from respondents on the following items and modules: social activity items, physical contact module, sexual interest module, get up and go assessment of physical function and a panel of biomeasures including, weight, waist circumference, height, blood pressure, smell, saliva collection, taste, and a self-administered vaginal swab for female respondents. The Core file also contains a count of the total number of drugs taken, and a variable for each observed therapeutic category, indicating whether the respondent reported taking one or more medications in that category. These variables are derived from the information in the medications file, and thus are guaranteed to be consistent with it. The Marital/Cohabiting History file (Dataset 3) contains one record for each marriage or cohabitation identified in Section 3A of the questionnaire. The Social Networks file (Datasets 4 and 5) contains one record for each person identified on the network roster. Respondents who refused to participate in the roster or who did not identify anyone are not represented in this file. The Medications file (Dataset 6) contains one record for each item listed in the medications log (including alternative medicines and nutritional products). Respondents who did not report taking any medications or who refused to participate in this module are not represented in this file. Lastly, the Sexual Partners file (Dataset 7) contains one record for each sexual partner identified in Section 3A of the questionnaire.

NACDA also maintains a Colectica portal with the NSHAP Core data across rounds 1-3, which allows users to interact with variables across rounds and create customized subsets. Registration is required.

The National Social Life, Health and Aging Project (NSHAP) is the first population-based study of health and social factors on a national scale, aiming to understand the well-being of older, community-dwelling Americans by examining the interactions among physical health, illness, medication use, cognitive function, emotional health, sensory function, health behaviors, and social connectedness. It is designed to provide health providers, policy makers, and individuals with useful information and insights into these factors, particularly on social and intimate relationships.

The National Opinion Research Center (NORC), along with Principal Investigators at the University of Chicago, conducted more than 3,000 interviews during 2005 and 2006 with a nationally representative sample of adults aged 57 to 85. Face-to-face interviews and biomeasure collection took place in respondents' homes. Round 2 interviews were conducted from August 2010 through May 2011, during which Round 1 Respondents were re-interviewed. An attempt was also made to interview individuals who were sampled in Round 1 but declined to participate. In addition, spouses or co-resident partners were also interviewed using the same instruments as the main respondents. This process resulted in 3,377 total respondents. The following files constitute Round 2: Core Data, Disposition of Round 1 Partner Data, Social Networks Data, Social Networks Update Data, Partner History Data, Partner History Update Data, Medications Data, Proxy Data, and Sleep Statistics Data.

Included in the Core files (Datasets 1 and 2) are demographic characteristics, such as gender, age, education, race, and ethnicity. Other topics covered respondents' social networks, social and cultural activity, physical and mental health including cognition, well-being, illness, history of sexual and intimate partnerships, and patient-physician communication, in addition to bereavement items. Data were also collected from respondents on the following items and modules: social activity items, physical contact module, sexual interest module, get up and go assessment of physical function, and a panel of biomeasures, including weight, waist circumference, height, blood pressure, smell, saliva collection, and taste.

The Disposition of Round 1 Partner files (Datasets 3 and 4) detail information derived from Section 6A items regarding the partner from Round 1 within the questionnaire. This provides a complete history for respondent partners across both rounds.

The Social Networks files (Datasets 5 and 6) contain one record for each person identified on the network roster. Respondents who refused to participate in the roster or who did not identify anyone are not represented in this file.

The Social Networks Update files (Datasets 7 and 8) detail respondents' current relationship status with each person identified on the network roster.

The Partner History file (Dataset 9) contains one record for each marriage, cohabitation, or romantic relationship identified in Section 6A of the questionnaire, including a current partner in Round 2 but excluding the partner from Round 1.

The Partner History Update file (Dataset 10) details respondents' current sexual partner information, as well as marital and cohabiting status.

The Medications Data file (Dataset 11) contains records for items listed in the medications log.

The Proxy Data files (Datasets 12 and 13) contain information from proxy interviews administered for Round 1 Respondents who were either deceased or whose health was too poor to participate in Round 2.

The Sleep Statistics Data files (Dataset 14 and 15) provide information on actigraphy sleep variables.

NACDA also maintains a Colectica portal with the NSHAP Core data across rounds 1-3, which allows users to interact with variables across rounds and create customized subsets. Registration is required.

The National Social Life, Health and Aging Project (NSHAP) is a population-based study of health and social factors on a national scale, aiming to understand the well-being of older, community-dwelling Americans by examining the interactions among physical health, illness, medication use, cognitive function, emotional health, sensory function, health behaviors, and social connectedness. It is designed to provide health providers, policy makers, and individuals with useful information and insights into these factors, particularly on social and intimate relationships.

The National Opinion Research Center (NORC), along with Principal Investigators at the University of Chicago, conducted more than 3,000 interviews during 2005 and 2006 with a nationally representative sample of adults aged 57 to 85. Face-to-face interviews and biomeasure collection took place in respondents' homes. Round 3 was conducted from September 2015 through November 2016, where 2,409 surviving Round 2 respondents were re-interviewed, and a New Cohort consisting of adults born between 1948 and 1965 together with their spouses or co-resident partners was added. All together, 4,777 respondents were interviewed in Round 3. The following files constitute Round 3: Core Data, Social Networks Data, Disposition of Returning Respondent Partner Data, and Proxy Data.

Included in the Core files (Datasets 1 and 2) are demographic characteristics, such as gender, age, education, race, and ethnicity. Other topics covered respondents' social networks, social and cultural activity, physical and mental health including cognition, well-being, illness, history of sexual and intimate partnerships and patient-physician communication, in addition to bereavement items. In addition data on a panel of biomeasures including, weight, waist circumference, height, and blood pressure was collected. The Social Networks (Datasets 3 and 4) files detail respondents' current relationship status with each person identified on the network roster. The Disposition of Returning Respondent Partner (Datasets 5 and 6) files detail information derived from Section 6A items regarding the partner from Rounds 1 and 2 within the questionnaire. This provides a complete history for respondent partners across both rounds. The Proxy (Datasets 7 and 8) files contain final health data for Round 1 and Round 2 respondents who could not participate in NSHAP due to disability or death.

The COVID-19 sub-study, administered to NSHAP R3 respondents in the Fall of 2020, was a brief self-report questionnaire that probed how the coronavirus pandemic changed older adults' lives. The COVID-19 sub-study questionnaire was limited to assessing specific domains in which respondents may have been affected by the coronavirus pandemic, including: (1) COVID experiences, (2) health and health care, (3) job and finances, (4) social support, (5) marital status and relationship quality, (6) social activity and engagement, (7) living arrangements, (8) household composition and size, (9) mental health, (10) elder mistreatment, (11) health behaviors, and (12) positive impacts of the coronavirus pandemic. Questions about engagement in racial justice issues since the death of George Floyd in police custody were also added to facilitate analysis of the independent and compounding effects of both the COVID-19 pandemic and reckoning with longstanding racial injustice in America.

The Study of Women's Health Across the Nation (SWAN), is a multi-site longitudinal, epidemiologic study designed to examine the health of women during their middle years. The study examines the physical, biological, psychological, and social changes during this transitional period. The goal of SWAN's research is to help scientists, health care providers, and women learn how mid-life experiences affect health and quality of life during aging. The data include questions about doctor visits, medical conditions, medications, treatments, medical procedures, relationships, smoking, and menopause related information such as age at pre-, peri- and post-menopause, self-attitudes, feelings, and common physical problems associated with menopause.

The study is co-sponsored by the National Institute on Aging (NIA), the National Institute of Nursing Research (NINR), the National Institutes of Health (NIH), and the NIH Office of Research on Women's Health. The study began in 1994. Between 1996 and 1997, 3,302 participants joined SWAN through 7 designated research centers. The research centers are located in the following communities: Detroit, MI; Boston, MA; Chicago, IL; Oakland and Los Angeles, CA; Newark, NJ; and Pittsburgh, PA. SWAN participants represent five racial/ethnic groups and a variety of backgrounds and cultures. This is the next phase of data collection after the original collection of the screening data (ICPSR 4368).

This collection includes screener data collected as part of the Study of Women's Health Across the Nation (SWAN), which is a multi-site longitudinal, epidemiologic study which began in 1994 and was designed to examine the health of women during their middle years. The study examines the physical, biological, psychological, and social changes during this transitional period. The goal of SWAN's research is to help scientists, health care providers, and women learn how mid-life experiences affect health and quality of life during aging. This data includes questions about doctor visits, medical conditions, medications, treatments, medical procedures, relationships, smoking, and menopause related information such as age at pre-, peri- and post-menopause, self-attitudes, feelings, and common physical problems associated with menopause. Also included in the data are background characteristics (age, race, occupation, education, marital status, and family size).

The SWAN study is co-sponsored by the National Institute on Aging (NIA), the National Institute of Nursing Research (NINR), the National Institutes of Health (NIH), and the NIH Office of Research on Women's Health. The screener dataset contains information from 16,142 women who responded to the SWAN cross-sectional screening interview during the period from 11/1/1995 through 12/1/1997 from the 7 clinical sites participating in the SWAN longitudinal study. The sites include Boston, Massachusetts, Pittsburgh, Pennsylvania, Oakland and Los Angeles, California, Detroit, Michigan, Newark, New Jersey and Chicago, Illinois. SWAN participants represent five racial/ethnic groups and a variety of backgrounds and cultures.

The Study of Women's Health Across the Nation (SWAN) is a multi-site longitudinal, epidemiologic study designed to examine the health of women during their middle years. The study examines the physical, biological, psychological, and social changes during this transitional period. The goal of SWAN's research is to help scientists, health care providers and women learn how mid-life experiences affect health and quality of life during aging. The data include questions about doctor visits, medical conditions, medications, treatments, medical procedures, relationships, smoking, and menopause related information such as age at pre-, peri- and post-menopause, self-attitudes, feelings, and common physical problems associated with menopause.

The study is co-sponsored by the National Institute on Aging (NIA), the National Institute of Nursing Research (NINR), the National Institutes of Health (NIH), and the NIH Office of Research on Women's Health. The study began in 1994. Between 1997 and 1999, 2,881 of the 3,302 women that joined SWAN were seen for their first follow-up visit. The research centers are located in the following communities: Detroit, MI; Boston, MA; Chicago, IL; Oakland and Los Angeles, CA; Newark, NJ; and Pittsburgh, PA. SWAN participants represent five racial/ethnic groups and a variety of backgrounds and cultures.

The Study of Women's Health Across the Nation (SWAN), is a multi-site longitudinal, epidemiologic study designed to examine the health of women during their middle years. The study examines the physical, biological, psychological, and social changes during this transitional period. The goal of SWAN's research is to help scientists, health care providers, and women learn how mid-life experiences affect health and quality of life during aging. The data include questions about doctor visits, medical conditions, medications, treatments, medical procedures, relationships, smoking, and menopause related information.

The study is co-sponsored by the National Institute on Aging (NIA), the National Institute of Nursing Research (NINR), the National Institutes of Health (NIH), and the NIH Office of Research on Women's Health. The study began in 1994. Between 1999 and 2001, 2,710 of the 3,302 women that joined SWAN were seen for their third follow-up visit. The research centers are located in the following communities: Detroit, Michigan; Boston, Massachusetts; Chicago, Illinois; Oakland and Los Angeles, California; Newark, New Jersey; and Pittsburgh, Pennsylvania. SWAN participants represent five racial/ethnic groups and a variety of backgrounds and cultures.

The Study of Women's Health Across the Nation (SWAN) is a multi-site longitudinal, epidemiologic study designed to examine the health of women during their middle years. The study examines the physical, biological, psychological, and social changes during this transitional period. The goal of SWAN's research is to help scientists, health care providers and women learn how mid-life experiences affect health and quality of life during aging. The data include questions about doctor visits, medical conditions, medications, treatments, medical procedures, relationships, smoking, and menopause related information such as age at pre-, peri- and post-menopause, self-attitudes, feelings, and common physical problems associated with menopause.

The study is co-sponsored by the National Institute on Aging (NIA), the National Institute of Nursing Research (NINR), the National Institutes of Health (NIH), and the NIH Office of Research on Women's Health. The study began in 1994. Between 2000 and 2002, 2,679 of the 3,302 women that joined SWAN were seen for their second follow-up visit. The research centers are located in the following communities: Boston, Massachusetts, Pittsburgh, Pennsylvania, Oakland and Los Angeles, California, Detroit, Michigan, Newark, New Jersey and Chicago, Illinois. SWAN participants represent five racial/ethnic groups and a variety of backgrounds and cultures.

The World Health Organization (WHO)'s Study on Global Ageing and Adult Health (SAGE) is a longitudinal follow-up of a cohort of ageing and older adults. SAGE has been built on the experience and standardized instruments of WHO's 2000/2001 Multi-country Survey Study (MCSS) and the 2002/2004 World Health Surveys (WHS).

These surveys focused on health and health-related outcomes and their determinants and impacts in nationally representative samples. These data will address data gaps on ageing, adult health and well-being in lower and middle income countries, whilst being comparable to surveys conducted in higher income countries (such as the United States' Health and Retirement Study (HRS), English Longitudinal Study of Ageing (ELSA), and the Survey of Health, Ageing and Retirement in Europe (SHARE)). One of the major drivers of this effort has been the lack of comparability of self-reported health status in international health surveys due to systematic biases in reporting, despite using similar instruments and attempts at making questions conceptually equivalent in translation. SAGE uses standard instruments developed over the last decade, a common design and training approach with explicit strategies for making data comparable to cover a wide range of issues that directly and indirectly impact health and well-being.

The survey methodology and research design has included a number of methods to address methods for detecting and correcting for systematic reporting biases in health interview surveys, including vignette methodologies, objective performance tests and biomarkers. A number of techniques have also been employed to improve data comparability, including using common definitions of concepts, common methods of data collection and translations, rigorous sample design and post hoc harmonization. The 2007-2010 SAGE Wave 1 data from six countries (China, Ghana, India, Mexico, Russia, and South Africa) is the follow-up survey project to the 2002-2004 WHO data, which constitutes Wave 0 of WHO's Study on Global Ageing and Adult Health (SAGE). A sample of these respondents from SAGE Wave 0 are included in this follow-up 2007-2010 SAGE Wave 1 in the six countries, with new respondents added to ensure a nationally representative sample.