when comparing risk factors, how many studies should be conducted? how many studies are matched to compare risk and effect how many studies are there of comparing risk factors in a systematic review? how many studies are in meta analyses what are risk factors for comparing risk factors how many studies are there that can be compared how many studies are there that compare intervention a to b how to compare the effects of both interventions how many studies compare the effects of intervention a vs. b how many studies have a b x y effect which risk factors have more significant effect on outcomes than interventions b, a, and b? comparing risks of two risk factors how many studies to compare two risk factors how many studies are there in a meta analysis what is the meta-analysis of risk factors which risk factor has the most significant effect effects of two risk factors in meta analysis how many studies are needed for meta-analysis what studies are comparing b and a how many studies to compare risk factors