Why wouldn't stem PhDs follow some bell curve of quality? I'm sure many PhDs that are leaving don't contribute but some of them do. I personally don't see a reason for it to be skewed for only PhDs which don't contribute to leave.

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recursive 5 hours ago | parent [-]

These things are not in conflict. It's possible that PhD quality has a regular distribution, and that most of them aren't contributing much.

	▲	dtdynasty 5 hours ago \| parent [-]
		I agree with this. I guess you already believe they follow a bell curve.Then from your former comment you also believe it's worth it to lose many PhDs that don't contribute to also lose the few that do. I guess the conflict is my value judgement that it's good to keep PhDs that don't contribute if it allows US to keep the ones that do contribute. I believe so for 2 reasons. - Distinguishing between contributors and non contributors at scale is difficult. - the value of research can be large from a few contributors.