What are the birth cohort studies? Cohort studies are a type of longitudinal research. They follow people's entire life course so it's possible to build a complete picture of a person. By comparing data from different cohort studies, we can chart social change across different generations and start to untangle the reasons behind it. The depth and breadth of these datasets make them one of the most valuable sources of information for social research, policy and practice. Each birth cohort study follows the lives of a group of people all born at the same point in time. Cohort subjects are surveyed in order to collect information on a variety of different things, such as physical and mental health, family circumstances, parenting, education, and employment.