An economist's research into the Nazi regime's dismissals of Jewish mathematics professors in the 1930s has led him to conclude that in PhD supervision, big is beautiful.
Between 1933 and 1934, about 18 per cent of all mathematics professors in Germany were stripped of their posts by the Nazis, including some of the most eminent scholars of the day.
Fabian Waldinger, assistant professor in the department of economics at the University of Warwick, studied the impact of those dismissals on the mathematicians' doctoral students.
He found that the students whose subsequent careers were most adversely affected by the dismissals were those who had been supervised by highly cited professors.
His paper, "Quality matters: The expulsion of professors and the consequences for PhD student outcomes in Nazi Germany", which will be published in the Journal of Political Economy, shows that the dismissals affected the doctoral candidates' chances of publishing a dissertation, becoming a professor and being highly cited.
Dr Waldinger said his research ruled out the possibility that the negative effect stemmed merely from the loss in numbers of professors and resulting higher student-teacher ratios.
He said he had studied Nazi Germany because it offered a "natural experiment" in the relation between university quality and PhD outcomes without the need to account for possible differences in the inherent quality of students at different institutions.
He noted that, prior to the Second World War, German PhD programmes were concentrated in a small number of institutions. During this time, Germany produced 20 Nobel laureates.
By contrast, modern Germany had spread out its PhD programmes and the quality of research conducted in its institutions had dropped.
The lesson for policymakers, he argued, was that the best way to foster future research excellence is to establish large PhD programmes in a small number of high-quality universities.
Read Dr Waldingers paper in full.