Answer:
Experimental and interventional studies
Step-by-step explanation:
Studies in medicine are classified into experimental (i.e., basic research), clinical, and epidemiological. In addition, clinical and epidemiological studies are subsequently divided into interventional or noninterventional. Both experimental and interventional randomized trials enable to compare the effects of a particular treatment with the control. Generally, a placebo is used as control. It is important to note that both types of studies are based on factual evidence, and their outcomes need to be testable and repeatable.