RESEARCH STUDY 9

RESEARCH STUDY 9.1: Dr.Farah is an educational psychologist who is interested in studying the potential causal relationship between doing homework and academic achievement.In January, Dr.Farah has her students report their fall GPA (a measure of academic achievement) and estimate how many hours they spent doing homework during a typical week in the fall semester.In May, Dr.Farah measures the same variables again (the estimated number of hours spent doing homework during a typical week in the spring semester and their spring GPA) .She finds the following correlations. A colleague of Dr.Farah's questions the internal validity of her causal claim.He is curious as to whether the relationship between homework and academic achievement could be explained by interest in one's classes.Specifically, he thinks that students who are interested in their classes will both do more homework and have higher GPAs.Which of the following is a solution to this possible threat to internal validity?

A) Dr. Farah should replicate her study.
B) Dr. Farah should also measure students' interest in their class.
C) Dr. Farah should measure students' interest in their class instead of time spent doing homework.
D) Dr. Farah should measure students' interest in their class instead of GPA.