A researcher examines a program looking at the effects of mentoring on poor readers' reading achievement. He looks at two different schools. One serves as the control and the other the experimental group. Both schools had reading achievement that was around the 50th percentile. During the time that the mentoring program is in place in the experimental group, a statewide reading initiative is started in randomly selected schools. The experimental, but not the control school is involved in the statewide reading initiative. At the end of the year, the experimental group does better than the control. From the information presented above, a likely threat to the internal validity of the study is:
A) Selection by mortality interaction
B) Mortality
C) Selection-history effect
D) Selection-maturation effect

Question

Quizplus · Accepted Answer

The selection-history effect is a threat to internal validity because the experimental group was exposed to an additional statewide reading initiative, which could have influenced their improved performance, rather than the mentoring program alone.

A Researcher Examines a Program Looking at the Effects of Mentoring