Читать книгу Abnormal Psychology - William J. Ray - Страница 124

It may seem simple to select subjects for an experiment. However, this is often a greater problem than it appears. The individuals selected for the study should be directly related to the hypothesis being tested. If you want to know if individuals with schizophrenia perform better on a memory test after drinking coffee, then of course you select individuals with schizophrenia. If you want to be able to apply the results to the population of all adults, then it is necessary for adults of all ages, genders, and ethnic backgrounds to be included in the study.

population: in a research study, the larger group of individuals to which the results can be generalized

Researchers use a variety of means for selecting participants. The best is some form of random sampling. You might choose every tenth person in the college directory, or every fourth person admitted to the ward for treatment of schizophrenia, for example. When the selection is not random—that is, every person is not equally likely to be chosen—then bias can appear.

Figure 3.7 How Do You Perform an Experiment?