An ex-post study is a research method that involves analyzing data and information after an event or phenomenon has occurred. This type of study is often used in social sciences and economics to understand the impact and outcomes of a particular policy, program, or event. Unlike ex-ante studies which are conducted before an event, ex-post studies allow for a more comprehensive and accurate assessment of the effects of a specific action. By examining past data and outcomes, ex-post studies provide valuable insights and lessons for future decision-making.