Case acts as its own control in which of the following study?: (A) Cross over study, (B) Retrospective study, (C) Prospective study, (D) Case control study
Answer is A. Advantages of cross-over study design ( Cross over RCT): Each patient serves as his own control. All patients can be assured that they will receive the new therapy sometime during the course of investigation ( Thus, no ethical issues). Economize the total number of patients.