Aresearcher conducts a study to test whether attending weekly support groups decreases depressive symptoms. based on this information only, is this an example of descriptive or analytic epidemiology?

Based on the information given, that is an example of Analytic epidemiology.

Explanation:

While descriptive epidemiology generates hypothesis, goes deep into answering questions and try to develop the causes, patterns or factors that increase the risk of disease, analytic epidemiology test those hypothesis trying to anser WHY and how something OCCURS. In this case, this study is testing whether attending weekly support groups decreases depressive symptoms. The key feature of analytic epidemiology is a comparison group.