b'AGING IN THE 21ST CENTURYLongitudinal Cohort Design is an important resource for understanding caus- Israel, Mexico, China, Japan, South Korea, India, The HRS sample has been built up over time.es of racial disparities in wealth and health, soBrazil, Northern Ireland, Scotland, and South Figure A-4 depicts the longitudinal cohortmaintaining the sample of minority participantsAfrica. The global network greatly enhances the sample design. The initial 1992 HRS cohortis a priority. To address this need, a new initiativevalue of each of its members, including the HRS consisted of persons born 1931 to 1941, wholaunched in the 2010 wave of data collectionitself, through sharing of ideas and methods. The were then aged 51 to 61. Members of this firstgreatly expanded the minority sample in the EBBinternational studies have attracted researchers HRS cohort, now in their 70s and 80s, haveand MBB cohorts.from a variety of disciplines and all parts of the been interviewed every two years since 1992.globe. The availability of comparably measured A second study was added in 1993, the AssetGoing Global data in other countries with different policy and Health Dynamics Among the Oldest Old, orThe success of the HRS ideaa publicly avail- structures, social environments, and histories AHEAD, which captured those born before 1924,able, multidisciplinary, longitudinal study of theprovides opportunities for comparative research who were 70 and older at the time. Then in 1998,older populationhas led to the proliferationto shed light on causal relationships that even the HRS and AHEAD cohorts were merged, andof sister studies. The HRS is now the model forlongitudinal analysis in a single country cannot two new cohorts were enrolled to bridge thea growing network of harmonized longitudinalaccomplish. The growth of these studies expands study age gaps for Americans over age 50. Theseaging studies around the worldincludingthe network of researchers using the HRS data birth cohorts are the Children of the DepressionEngland, Ireland, 20 European Union countries,and contributing innovative measurement ideas. Era, or CODA, for those born 1924 to 1930, and the War Babies, for those born 1942 to 1947. Without refreshment, the HRS sample wouldFIGURE A-5HRS scientific productivityage quickly and become irrelevant to pre-retire-ment ages. So HRS now employs a steady state design, replenishing the sample every six years3000with younger cohorts. In 2004, the HRS added the Early Baby Boomers (EBB), born 1948 to 1953,2500and in 2010 added the Mid Baby Boomers (MBB), born 1954 to 1959. The Late Baby Boomers (LBB),2000born 1960 to 1965, were added in 2016. For all cohorts, both members of a couple are included in 1500the sample. To constrain costs, study recruitment was reduced in the steady state by nearly half from1000the levels of the original HRS cohort. This meant that lower numbers of minority households in the500more recent cohorts became a concern. The HRS 01995 2000 2005 2010 2015ReportsDissertationsBooks/book chaptersJournal articles 14'