Here is what you should do when you want to design a study to explore an idea or question:
You should carefully formulate your question and decide exactly what pieces of information are necessary to answer it.
You must determine the population of interest and select a random sample of objects or people from the population.
You must be sure that you do not unintentionally bias your sample by making it more likely that some members are included than others.
You must collect your information in an objective fashion. The procedure for gathering the information must be objective and standardized. Questions must be unambiguous.
If several different conditions are to be compared, you must ensure that the subjects are randomly allocated to the groups.
You must prevent the subjects and investigators from allowing their personal prejudices to influence the outcome of the investigation.