A friend emailed me a copy of a recent unpublished meta-analysis that doesn’t sit too well with La Griffe du Lion‘s fundamental law of sociology. The authors conducted a follow up to Roth et al.(2001)‘s massive meta-analysis, a meta-analysis which was cited by Rushton and Jensen in defense of their hereditarian position (e.g. Rushton and Jensen, 2006). While finding a 1.1 SD Black-White gap, Roth et al. (2001) noted that they were unable to “assess the influence of time on standardized ethnic group differences” and that they “tried to control for the influence of time by choosing the most recent studies when there was an option.” The authors of this meta-analysis coded for decade, limiting their sample to individuals above the age of 16, and found that as of the 90s the gap in non selected samples was 0.8 SD, down one third from the 70s. They went onto interpret the findings as support for a sociocultural origin of differences and ended their paper on a political note: “Policy makers are warranted to continue to further support and reinforce these developments through equality and affirmative action policies that increase opportunity for minority ethnic groups, and that promote a pro-diversity perspective in organizations.” (For reference, here is a list of meta-analyses of the Black-White gap in industry; herein (table 12.5) is a list of mean d values on an assortment of cognitive assessments.)
I don’t feel like critically commenting on this study, but I would note that one gets out of a meta-analysis what one puts into it and that it’s clear that the authors of this study did not include some large samples with large d’s that have been fairly invariant across time (e.g., the SAT and GRE). I would also add that the results are consistent with an interpretation of no change (comparing the difference in the 60s to that in the 90s).