**Representativeness of Samples**

The need for choosing the right sample for a research investigation cannot be overemphasized. We know that a sample will rarely be the exact replica of the population from which it is drawn. For instance, very few sample means (*X*) are likely to be exactly to the population means (). Nor is the standard deviation of the sample (*S*) going to be the same as the standard deviation of the population (). However, if we choose the sample in a scientific way, we can be reasonably sure that the sample statistic (e.g. *X, S, *or* S ^{2}*) is fairly close to the population parameter (i.e., , , or

^{2}). To put it differently, it is possible to choose the sample in such a way that it is representative of the population. There is always the slight probability, however, that sample values might fall outside the population parameters.

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