ABSTRACT
A sample is that fraction of the population that is actually studied. In almost all situations, the statistical population of interest is big, and we rarely have resources to study all the subjects. Even if the resources are unlimited, we can only study existing cases-the future cases and many of the past cases cannot be studied. And the irony is that the conclusions from the empirical studies are drawn, and we think they would be applicable to future cases. Thus, the sample remains an integral part of medical research framework.
