A researcher has conducted an experiment in which she assigned all of her students four hours of homework the night before a test; in order to see what effect the extra stress has on test performance. The study is flawed because the researcher did not include a(n) __________
A) control group.
B) experimental group.
C) independent variable.
D) dependent variable.

Question

Quizplus · Accepted Answer

The study is flawed because the researcher did not include a control group, which is necessary to compare the effects of the treatment (four hours of homework) with the effects of no treatment or a placebo. Without a control group, it is difficult to determine whether any changes in test performance were due to the treatment or other factors. The presence of experimental and dependent variables is implied by the design of the study but does not address the issue of lacking a control group.

A Researcher Has Conducted an Experiment in Which She Assigned