Dependent Variable

The variable measured in an experiment or study; what the experimenter measures.

When conducting research, a psychologist typically takes two or more similar groups of people or animals and exposes them to different treatments or situations. Then the researcher monitors a behavior of interest to see whether that behavior differs from one group to the next. This measurement is the dependent variable. A single experiment may involve more than one dependent variable.

When specifying the dependent variable, it must be clearly defined and measurable. In one experiment, researchers gathered a group of business executives who displayed evidence of Type A behavior (e.g., nonstop working, aggressiveness, and competitiveness). The researchers divided the executives into subgroups and either exposed them to a small amount of information regarding the health hazards of such behavior, provided them with support groups, or offered a course in stress management. The dependent variable was a score on a test that reflected Type A tendencies. Although personality is so complex that it cannot really be described by a single score, the test for Type A behavior provides a measurement that is objective and measurable. The executives who took the stress management course scored lower than those in the support groups; the highest test scores occurred in the group with the least exposure to information about stress management. The researchers concluded that the executives' test scores, the dependent variable, changed differently, depending on their group.