Great post. Would also be interested in seeing a breakdown of school strength across the referrals. And did you count Stanford as Ivy League? :)
Yeah, because I went there :). It was super subjective, but I'm sure that changing the details wouldn't change the conclusion.
Aha. 'Because I went there'. If your initial hires (presumably from your personal network) were from similarly highly ranked schools, then you have a strong correlation between social networks and school strength. Note that when no one knows the hire, school strength turns out to be irrelevant.
I would imagine that it's hard to separate cause from effect in the case of well-known schools and employment performance. The cumulative benefits of working challenging, rewarding jobs should pile up throughout a career. Naturally folks with an easy-to-sell pedigree are going to have a good shot at securing those jobs.