The study in which investigators attempt to trace an effect back to its cause is known as

Ex post facto research traces an observed effect backward to its already-existing cause.

Survey research gathers current opinions and characteristics from a sample of respondents.

Historical research reconstructs past events from records rather than tracing effect to cause.

Summative research evaluates the final impact of a completed programme, not causal tracing.

In ex post facto studies the presumed cause has already occurred and cannot be manipulated.

Its Latin name literally means from what is done afterwards.