1. A recent overview, which includes all case control studies, reports a highly significant duration-related effect of early OC use on premenopausal breast cancer. 2. In what is known as a case control study, health workers will compare the therapies given to those who survived and those who died. 3. The American Health Foundation used a different kind of scientific tool known as case control studies. 4. The design of case control studies, looking at past events, generally prevents definitive conclusions. 5. The study was of a type that epidemiologists call a case control study. 6. The study was a type known as case control. 7. The CDC experts had hoped to release preliminary findings on a case control study before leaving Hong Kong. |