Search Results Use the search box below to revise your search, or start a new search. Studies (2) Variables Publications Your query returned 2 studies. Series results are grouped under the most relevant study. Ungroup series results to view all results. Sort by: Study Relevance Title A-Z Released/Updated Time Period Most Cited in ICPSR Bib. Variable Relevance 1. English Longitudinal Study of Ageing (ELSA) (ICPSR 139) National Centre for Social Research (NatCen); University College London; Institute for Fiscal Studies (IFS) 2. Cross-National Equivalent File (CNEF), 1970-2009 (ICPSR 145) Cornell University. Department of Policy Analysis and Management; University of Michigan. Institute for Social Research. Panel Study of Income Dynamics; German Institute for Economic Research (DIW Berlin); et al.