9.60 Political bias in academia and a paired-samples t test: The following is an excerpt from the abstract (brief opening summary) from a published research study that examined a reported bias against conservatives in American academia (Fosse et al., 2011).

The American professoriate contains a disproportionate number of people with liberal political views. Is this because of political bias or discrimination?... We sent two emails to directors of graduate study in the leading American departments of sociology, political science, economics, history, and English. The emails came from fictitious students who expressed interest in doing graduate work in the department.... We analyze responses received in terms of frequency, timing, amount of information provided about the department, emotional warmth, and enthusiasm toward the student. (p.1)

One of the fictional emails was from a fictional student who mentioned working on the presidential campaign of John McCain, a well-known conservative, and one was from a fictional student who mentioned working on the presidential campaign of Barack Obama, a well-known liberal. The researchers conducted a series of paired-samples t tests but did not find statistically significant differences on the various measures between rating of the conservative and liberal students.

1. Why is this a within-groups design?