<p>As an example, I took the top 20 EE departments on the US News list and tallied where their faculty got their PhDs. In almost all cases, the majority (and in some cases 70%+) of their PhDs were from the top 4 programs: MIT, Stanford, Berkeley, and Caltech. There is a steep dropoff after that. For example, out of 67 MIT EE faculty, 32 came from MIT, 12 from Stanford, 9 from Berkeley, and just 14 from other places. Out of 49 Berkeley EE faculty, 11 came from Berkeley, 10 from MIT, 7 from Stanford, 5 from Caltech, and 16 from other places. Out of 43 Stanford faculty, 15 came from Stanford, 10 from Berkeley, 6 from MIT, 2 from Caltech, and 10 from other places.</p>