Ex-post facto research is a non-experimental research method in which the investigator studies the possible causes and effects of an event or behavior after it has already occurred. The term "ex-post facto" is derived from Latin, meaning "after the fact." In this type of research, the independent variable has already occurred or cannot be manipulated by the researcher. Instead of creating experimental conditions, the researcher examines existing differences among individuals or groups and attempts to identify relationships between variables. Ex-post facto research is widely used in psychology because many psychological, social, educational, and biological variables cannot be ethically or practically manipulated. The primary concept of ex-post facto research is based on observing naturally occurring situations rather than controlling or manipulating variables. Researchers begin with an observed outcome or dependent variable and then look backward to investigate possible factors that may have contributed to that outcome. For example, a psychologist may compare individuals with depression and those without depression to examine whether childhood trauma, family environment, or stressful life events are associated with the disorder. Since these experiences have already occurred, the researcher cannot assign participants to different conditions but can only study existing differences. The meaning of ex-post