1) Internal validity
Answer: There are many merits of the RCT for study design and it also based on the internal validity. The internal validity is based on the truth within a study. The study is internally valid if the study’s conclusions represent the truth for the individuals studied because the results were not likely due to the effects of chance, bias, or confounding because the study design, execution, and analysis were correct. The statistical assessment of the effects of chance is meaningless if sufficient bias has occurred to invalidate the study. All studies are flawed to some degree.