A university conducts a series of surveys in which subjects are drawn from first year and graduating students and finds that graduating students demonstrate much higher rates of approval for the university (in terms of whether they think the classes were relevant,the instructors were competent,etc.).The university then claims that more experience with the university leads to higher approval.What source of internal invalidity has the university not considered?
A)selection bias
B)mortality
C)noncomparable groups
D)regression

Question

Quizplus · Accepted Answer

Selection bias is a source of internal invalidity that occurs when the groups being compared are not equivalent at the start of the study. In this case, the university is comparing first-year students to graduating students. However, it is possible that the graduating students are more likely to approve of the university because they are more motivated or have a better understanding of the university's offerings. This would lead to a biased comparison, as the graduating students would be more likely to approve of the university regardless of their experience with it.

A University Conducts a Series of Surveys in Which Subjects