Was the frame of sample appropriate in addressing the selected population?
Was recruiting process for the study samples proper?
Was the number of samples being adequate?
Was the study setting along with subjects described clearly?
Was the analysis of data performed with enough detail of the sample identification?
Were accurate procedures applied for confirming the study condition?
Was the study condition analyzed acceptably and reliably for each participant?
Was the rate of response satisfactory, and if not, was the less response rate handled appropriately?
Was there a suitable statistical analysis?