fixed effects

Fixed effects are a statistical method used to control for variables that do not change over time within the same entity (like a person, company, or country). By accounting for these constant characteristics, fixed effects help isolate the impact of variables that do change over time, ensuring that results are not biased by unchanging factors. This technique essentially compares each entity to itself over different periods, removing the influence of factors that stay constant, so researchers can better understand how changing factors influence outcomes within individual entities.