Ex post facto research, also known as retrospective research, is a type of research in which the researcher studies events that have already occurred. The term "ex post facto" is Latin for "after the fact," which refers to the fact that the research is conducted after the events in question have taken place. The term "post mortem" is used to refer to this type of research because it is similar to a medical examination of a dead body, in which the cause of death is determined after the fact. Both ex post facto research and a post mortem examination are used to understand and explain events that have already occurred.

There are differences between retrospective and prospective studies and both of them are called Ex Post Facto.

It means after fact from thing done afterwards...

Is defined as research method that looks into how an independent variable