An experimenter is interested in the effects of watching TV on children's cognitive development. She recruits two groups of 20 boys, one containing children who regularly watch TV for two hours a day, and the other comprised of children who never watch TV. When tested, the groups are significantly different in problem-solving ability. Which of the following is a threat to the validity of these results?
A) The experimenter hasn't taken account of which channel the children watch.
B) The groups are initially non-equivalent.
C) Two hours isn't long enough to show any effects of TV watching.
D) The study should have included both boys and girls.

Question

Quizplus · Accepted Answer

The fact that the groups are initially non-equivalent suggests that the experimenter did not properly control for other variables that may have influenced the results. This threatens the validity of the study because it could mean that the observed differences in problem-solving ability are due to factors other than TV watching.

An Experimenter Is Interested in the Effects of Watching TV