You're assuming that the schools don't in themselves add value beyond signalling.
Even after adjusting for academic achievement students from top-tier university do better post-university, as this broadly tends to hold true across subjects. Of course this could be purely be down to signalling effect, but if so it would imply signalling has as strong impact across all industries not just a handful of professional ones.
Even after adjusting for academic achievement students from top-tier university do better post-university, as this broadly tends to hold true across subjects. Of course this could be purely be down to signalling effect, but if so it would imply signalling has as strong impact across all industries not just a handful of professional ones.