Suppose you perform an experiment that compares the performance of an experimental group and a control group. You find that the mean of the experimental group is higher than the mean of the control group. Does this prove that the treatment enhanced performance?
A) Yes, because the experimental group did better as a whole than the control group
B) No, because you must compare variances, not means
C) No, because the difference between the group could have occurred by chance, even if it was not very likely i.e., less than .05)
D) Yes, because group averages are the traditional measure to use to compare two groups

Question

Quizplus · Accepted Answer

The correct answer is C because simply observing a difference in means between an experimental group and a control group does not prove causation or that the treatment enhanced performance without considering the statistical significance of the difference. This difference could have occurred by chance, and statistical tests are needed to determine if the observed difference is unlikely to have occurred if there were no true effect of the treatment.

Suppose You Perform an Experiment That Compares the Performance of an Experimental