At most public universities everyone’s salary is a matter of public record. It’s always fascinated me that we don’t talk about this more often. It means it is straightforward to look at the total variance in people’s salaries in the same role and test different ideas for what might explain the differences in compensation between different people in the same role. So let’s take a look!
In my own department there are ~45 faculty with research appointments and entries in our school’s 21-22 salary database: Eight assistant professors, fifteen associate professors, and twenty-one full professors. Since assistant professors want to get promoted to associate professor and associate professors want to get promoted to full professors, the simplest model I can think of is to look at how well professor rank predicts salary.
Okay, so our extremely naive model is clearly on to something: average salary increases as people get promoted. But also salaries are much more widely distributed amongst full professors than among assistant professors. Lots of things that could be driven by. But what about the classic “let’s boil down research productivity to a single metric”: the h-index? Only 36 of the 45 professors in my department have google scholar profiles. But that’s not the big problem.