DOI: 10.3886/icpsr28502.v2
title: WHO Study on Global AGEing and Adult Health (SAGE): Wave 0, 2002-2004
title: Version 2

description: 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 aim to 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 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 2002-2004 WHS data from six countries (China, Ghana, India, Mexico, Russia, and South Africa) constitute Wave 0 of WHO's Study on Global Ageing and Adult Health (SAGE). A sample of these respondents were included in the follow-up 2007-2010 SAGE Wave 1 in these six countries, with new respondents added to ensure a nationally representative sample.
description: The specific aims of SAGE as currently formulated are: To obtain reliable, valid and comparable data on levels of health in a range of key domains for older adult populations; to examine patterns and dynamics of age-related changes in health using longitudinal follow-up of survey respondents as they age, and to investigate socio-economic consequences of these health changes; to supplement and cross-validate self-reported measures of health and the anchoring vignette approach to improving comparability of self-reported measures, through measured performance tests for selected health domains; to collect data on health examinations and biomarkers to improve reliability of data on morbidity, risk factors and monitor effect of interventions. Additional objectives include: To generate large enough cohorts of older adult populations and comparison cohorts of younger populations for follow-up of intermediate outcomes, monitoring trends, examine transitions and life events, and address relationships between determinants and health and health-related outcomes; to develop a mechanism to link survey data to data from demographic surveillance sites; to build linkages with other national and cross-national ageing studies; and, to provide a public-access information base to engage all stakeholders, including national policy makers and health systems planners, in planning and decision-making processes about the health and well-being of older adults. In addition, close linkages with the International Network of field sites with continuous Demographic Evaluation of Populations and Their Health (INDEPTH) in developing countries will ensure that detailed methodological exercises can be undertaken to validate self-reported morbidity and survey mortality data.
description: The data are not weighted, but contain four weight variables which users may wish to apply during analysis. Household weights for analysis at household level include HHWEIGHT (Household probability weight) and HHPSWEIGHT (Post stratified household probability weight). Individual weights for analysis at person level include PWEIGHT (Individual probability weight) and PSWEIGHT (Post stratified individual probability weight). These weights were based on the selection probability at each stage of selection. Weights were post-stratified by age group and sex according to the UN population estimates and locality based on UN Population Division estimates.
description: Response Rates: The response rates from the WHS for the six SAGE countries at the Household and Individual Levels were as follows:
China: 92.8 percent and 100 percent;
Ghana: 72.8 percent and 96.7 percent;
India: 95.6 percent and 97.1 percent;
Mexico: 96.5 percent and 99.7 percent;
Russian Federation: 99.8 percent and 99.9 percent;
South Africa: 80.1 percent and 90 percent
description: The targeted sample sizes for each country are as follows: China 4300, Ghana 5662, India 10750, Mexico 40000, Russian Federation 4427, and South Africa 3157.
Probability sampling techniques were used to obtain the sample, with suggested sample sizes of 5000 households in each country. Some countries prioritized the ability to analyze data at the local level and had the financial resources to support the required larger sample size.
description: Datasets: 
DS1: WHO Study on Global AGEing and Adult Health (SAGE): Wave 0, 2002-2004
description: Nationally representative samples of adults aged 18 years and older, residing within individual households, institutionalized population excluded, in the following countries: China, Ghana, India, Mexico, Russia, and South Africa. Smallest Geographic Unit: country
description: computer-assisted personal interview (CAPI); computer-assisted telephone interview (CATI); face-to-face interview; paper and pencil interview (PAPI)Please note that the related data collection featuring Wave 1 of SAGE: WHO Study on Global AGEing and Adult Health (SAGE): Wave 1, 2007-2010, will be available as ICPSR #31381.Variables were removed to prevent disclosure risk and preserve respondent anonymity.For additional information on the WHO Study on Global AGEing and Adult Health (SAGE): Wave 0, 2002-2004, please visit the WHO Study on Global AGEing and Adult Health (SAGE) Web site.