Abstract :
Calculating and justifying sample size for a study can be an intimidating task for new researchers. Nonetheless, it is one of the most important aspects of any study. In this article, we aim to provide basic and fundamental information about calculating sample size which should be helpful for most research studies. In research studies, a sample has to be obtained if it is not possible to include all the subjects in the study population. For example, if you want to study the prevalence of smoking in the first year medical students of your medical college, you could just ask all of the students in that class to fill the questionnaire, without doing any sampling. However, if you want to know the prevalence of smoking in all the medical students of Pakistan, then it will be very difficult for you to have each and every medical student to fill your questionnaire. In that case you will need to do sampling.
