How does the concept of 'moderator variables' relate to null findings in research design?

Answer

Negative results can prompt deeper inquiry into conditions that influence when an effect is present or absent.

If an intervention shows a null result in a general population, the negative finding guides researchers to test specific subgroups or conditions (moderator variables) that might reveal when the effect truly functions.

How does the concept of 'moderator variables' relate to null findings in research design?
databasevaluedataResultnull