The term clinical trial is used in different contexts and sometimes with different meanings. While we are looking for the prevalence of a disease over time, the cross-sectional study freezes a specific moment in time, it aims to find the same type of reports that can be viewed with the "moving pictures" of the cohort study, but at much lower costs. Similarly, In a cross sectional study a specific group is observed to see if a substance or activity, such as smoking, is related to the events to be investigated, for ...