The participants who give their informed consent to participate in a study are defrauded if the study is too small to yield useful results. Statistics can be helpful in determining the correct sample size. In order for statistics to be helpful however, the investigator must have a working idea of the magnitude of difference between the new treatment and the usual treatment. Once the investigator makes a commitment to the magnitude of difference, the statistician can easily calculate the sample size for the study. Recap Statistics quantifies variability and aids the researcher in distinguishing between chance and cause.
Observational studies suggest questions.
Planned experimental studies answer questions. Bias can enhance or diminish the real differences between treatments. The proper study size is fixed if there is an understanding of the magnitude of difference between two treatment options.