SAMPLING

Although you may want to draw conclusions about all rats or all residents of Los Angeles, you certainly do not want to have to train all of the world's rats or personally visit every Los Angeles home. What you want to do is to study some rats or some people, draw conclusions based on what you have observed for them, and have the conclusions apply to the population in which you are really interested.

The rats or people (or other creatures or objects) that you actually observe in your study are called the sample . You can select a sample from a particular population in countless ways. How you do it is very important because if you do not do it correctly, you will not be able to draw conclusions about your population. That is a pretty serious shortcoming. For the most part, interesting studies are those that allow you to draw conclusions about a much larger group of subjects than that actually included in the sample.