Sample

Sampling is a crucial technique in the science of statistical analysis. It represents a compromise between a researcher collecting all possible information on some topic and the amount of information that he or she can realistically collect. For example, in the example used above, the ideal situation might be for a researcher to collect data from every single 11th grade student in the United States. But the cost, time, and effort required to do this kind of study would be enormous. No one could possibly do such a study.

The alternative is to select a smaller subset of 11th grade students and collect data from them. If the sample that is chosen is typical of all 11th grade students throughout the United States, the data obtained could also be considered to be typical. That is, if the average 11th grade student in the sample studies English literature two hours every evening, then the researcher might be justified in saying that the average 11th grade student in the United States also studies English literature two hours a night.