Hypothesis Testing: An Introduction
R. B. G. Williams · 1984
Sampling is undertaken in order to secure information about a population that for reasons of time or otherwise cannot be studied in full. From the sample inferences are made concerning the nature of the population. Thus, if the sample mean is 35 units, the inference might be drawn that the population mean is equal to 35 units. If the variance of the sample is 5 units, the variance of the population might be inferred to be also 5 units.