how would you even measure that without the causal effects of "we only hired people from these schools" not being an interfering factor? my own personal experi

how would you even measure that without the causal effects of "we only hired people from these schools" not being an interfering factor? my own personal experience (from > 20 years in professional workforce) is that there's generally very little correlation between work performance and academic pedigree. For entry level positions, I've seen a bit, but after, say, 5-8 years, people are generally either really good at what they're doing, and are getting better, or they're struggling. I've not seen any correlation between the strugglers/non-strugglers and where they went to school, or indeed, to some extent, what they studied.