Appropos of discussions going on in my department about the quality of our graduate education, here is a list of where the tenure-track faculty in top CS departments got their PhDs. (Thanks to John Iacono for helping put this together!) The first several rows are taken from the top of the most recent US News rankings. Toronto is arguably the top CS department in Canada. We looked up Brooklyn Poly on a lark. The columns are mostly the same, except we removed Caltech and Georgia Tech
(which had almost no PhDs in any department) and added Harvard (the most highly represented non-top-10 department). Dots means zero. We counted only full-time tenure-track faculty—no research faculty, adjuct faculty, lecturers, or emeriti.
Please do not take this data as gospel. We extracted it from whatever sources we could find on the web; I'm positive there are mistakes.
This table reflects baldy on my department in two ways. Looking at the UIUC row, we see that a slight majority of the faculty did not get PhDs from top-10 departments. More significantly, the UIUC column shows that we're historically abysmal at getting our PhDs into top-10 departments. We faculty at UIUC like to compare ourselves with MIT and Stanford, but Wisconsin does a significantly better job of placing students in top departments than UIUC.
We should do better!
Update (Dec 12): Let me add two major caveats about these numbers. First: Different departments define "computer science" differently. We chose to count tenure-track faculty in computer science departments only, regardless of the area in which they received their PhDs. So computer architechts with computer science degrees from UIUC who work in Cornell's ECE department are not counted, but Harvard-degreed psychologists working in the CS department at CMU are. Second: Faculty accumulate in computer science departments over a period of decades. As best, these numbers reflect years-long historical trends, not current departmental quality. Restricting attention to assistant professors might reveal a more accurate picture.