Which one of the following statements regarding prepost clinical trial is most appropriate ?
Ans. is 'c' i.e., They use the patient as his or her own control Pre-post clinical trial o Pre-post clinical trials 'or' before and after comparison studies are Non randomized trials in which we compare the incidence of disease before and after introduction of a preventive measure. o The event which took place prior to the use of the new treatment or preventive procedure are used as a standard for comparison. In other words the experiment serves as its own control : this eliminates viually all group differences. o It is often used in assessing whether knowledge, attitudes or preexisting risk behavioral change when a subject is assigned to an intervention.
They cannot be randomized
They are useful in studies involving moality
They use the patient as his or her own control
They are usually easier to interpret than the comparable parallel clinical trial