Overview Interventional studies are prospective studies designed to evaluate the direct impact of therapies or preventative measures by assigning subjects to intervention groups 2 types of interventional studies login to view 4 more bullets Highest quality if login to view 3 more bullets Clinical Drug Trials 4 phases for clinical trials evaluating new drugs login to view 16 more bullets Factorial Design Randomizes patients into different interventions with 2 or more variables being studied in each intervention login to view 2 more bullets Crossover design Participants alternate receiving intervention and placebo Participants act as own controls login to view 3 more bullets