**3. Selection of trial subjects**

Patient selection for any clinical trial is a very critical point. When choosing the inclusion criteria, the researcher should think that what factors are important to the research question and include the main characteristics of target population. The researcher should be careful that excessive exclusion may degeneralize the study. The caseness of pediatric subjects should be confirmed by a pediatrician. When working on pediatric psychiatric patients, the sensitivity is much more, the eligibility of subjects must be clearly defined in the inclusion and exclusion criteria. Furthermore, the diagnosis must be confirmed by a child and adolescent psychiatrist based on the latest version of diagnostic and statistical manual of mental disorders (DSM). In psychiatry trials, documentation and history of the diagnosis are usually required [6, 7].
