“Closing the social class achievement gap” paper

A colleague at NCSU asked my opinion of this paper, which tests the effect of a diversity education intervention on GPA.

In general, the paper is quite detailed and the analysis carefully done. But the authors find that their intervention has quite an impact:

This main effect was qualified, however, by the predicted interaction of generation and condition [F(1,125)=4.34, p=.039]. Unpacking the interaction, we found that in the standard condition, a gap of .30 grade points emerged between first-generation and continuing-generation students [F(1,61)=6.56, p=.01]. In the diversity education condition, however, the two groups were not significantly different [F(1,59)=.004, p=.95]. In fact, the achievement gap in the diversity education condition was 63% smaller than the gap in the standard condition [Cohen’s d=.70]

The intervention is participation in a one-hour student panel at college entry. I’m currently working on a review of field experiments in postsecondary research, and this effect size seems implausibly high: attending a one-hour panel at the beginning of school increases GPA for some students by almost 1/3 of a grade point?

I am fairly confident that this result is a fluke and will not be replicated. If it is replicated, then the authors have developed a revolutionary postsecondary intervention.