In a nonequivalent control group design, an analysis of covariance
A) removes the effects of all pre-existing group differences.
B) indicates what the posttest means would look like if known pre-test differences between groups are removed.
C) has lower power than an analysis of variance design.
D) is the appropriate statistic for studies that use a matching procedure.

Question

Quizplus · Accepted Answer

An analysis of covariance (ANCOVA) is used in nonequivalent control group designs to control for pre-existing differences between groups by statistically removing their effects on the posttest scores. The ANCOVA estimates what the posttest means would look like if the known pre-test differences between the groups were removed, thus allowing for a more accurate assessment of the treatment effect.

In a Nonequivalent Control Group Design, an Analysis of Covariance