When collecting data for our study, the first thing we need to do, is to decide about the size of our sample; and the method of drawing this sample from the population of interest. Generally, it depends upon various factors like the nature and composition of the population of interest, the availability of resources and the validity of our study. Usually, large samples are considered more efficient in terms of validity than small samples. But they will consume more efforts and more resource as compared to smaller samples. So, if our time and resources are limited and validity is not our major concern than we should choose a smaller sample size. Similarly, we should take into consideration the composition of our population when selecting a sample from it. In case we fail in choosing the right type of our sample, it will badly affect the results and validity of our study. Normally, we can draw our sample from the population of interest in either of the following two ways:
Sampling without Replacement
