I am writing a proposal paper and am on the methods section. My mock research study is on the affects of gut health on mental health (specifically the affects of paleo diet with fermented foods on depression and anxiety). I have chosen to used stratified random sampling (strata being: depressed individuals, anxious individuals, individuals with both). The study design is a single blind randomized controlled trial-- a pre-test/post-test control group design (I believe this is a between subjects design, correct?). The instruments used to assess symptoms are the GAD-7 and the Center for Epidemiologic Studies Depression Scale. How do I know what kind of statistical test to use, and how will the results of the analysis be used to evaluate the hypothesis?