with subjects that are at risk to have the outcome or disease of interest and identifies the outcome starting from where the subject is when the study starts to the past of the subject to identify the exposure. Retrospective use records: clinical, educational, birth certificates, death certificates, etc. but that may be difficult because there may not be data for the study that is being initiated. These studies may have multiple exposures which may make this study difficult. On the other hand, an example of a retrospective cohort study is, if a demographer was examining a group of people born in year 1970 who have type 1 diabetes. The demographer would begin by looking at historical data. However, if the demographer was looking at ineffective data in attempts to deduce the source of type 1 diabetes, the demographers results would not be accurate. See also Age grade Bureau of Labor Statistics Case mix Cohort study Generational cohort National Longitudinal Surveys Prospective cohort study References External links Cohort in a glossary, U.S. Bureau of Labor Statistics Division of Information Services Centre for Longitudinal Studies - the UK resource centre for national birth cohort studies. Actuarial science Biostatistics Demography Applied statistics