What difference does the quality of education make for student outcomes? Establishing a causal relationship is difficult especially for PhD students, because it is likely that the best students are drawn to the best departments, so that a positive correlation between departmental strength and students’ success is at least in part due to a selection effect. An article in the latest issue of the Journal of Political Economy uses a smart identification strategy, namely the expulsion of mathematics professors in Nazi Germany as an exogenous shock to faculty quality. The abstract sums up the main results:
I investigate the effect of faculty quality on PhD student outcomes. To address the endogeneity of faculty quality I use exogenous variation provided by the expulsion of mathematics professors in Nazi Germany. Faculty quality is a very important determinant of short- and long-run PhD student outcomes. A one-standard-deviation increase in faculty quality increases the probability of publishing the dissertation in a top journal by 13 percentage points, the probability of becoming a full professor by 10 percentage points, the probability of having positive lifetime citations by 16 percentage points, and the number of lifetime citations by 6.3.
These effects look sizeable but maybe not as large as we, as professors, like to think. Self-selection is probably as strong a determinant of success as departmental quality, possibly even more.
As an aside, this research is a nice illustration of the causal inference trend that is well established in economics and is catching up quickly also in political science. In this regard, see also this previous post.