1) the only two publicly available surveys to this detail are 2013 and 2015
2) The **** that hit the fan is 2013 over this was in large part why they repeated in 2015 and why they dont release after that
3) and all the issue was does a prestigious school help, and the answer is yes: Why, How, to What Extent is unknown and variable in numerous ways across multiple schools
4) medical profession and the schools by extension are conservative in the sense that change does not come quickly. It takes a generation (20-30 years) for any major "cultural" changes. For example, the merger of residency governance, was started back in 1995 under a project called "physician 2015" that was attempting to put MD, DO, and DPM under a single umbrella. The only thing that came to that was the MD/DO residency merger and that was finally prompted by the number of open residency slots under DO.
5) yeah I am old, been involved with medical admissions since the 1970s and historical understanding of the changes does matter
Sounds reasonable! So what you are saying is that the table in every annual edition of Using MCAT Data is citing to the same survey taken in 2015? Okay. And I honestly do appreciate the perspective that comes with your many years of experience. I also get that old habits die hard.
Being still wet behind the ears, please indulge me this one question, though -- as I said before, I understand that MCATs and GPAs are cited as "highest importance" academic metrics, and it's obvious that it's true based on how high those metrics are for the top 90+% of matriculants at top schools, how truly rare relatively low GPAs and MCATs are at those schools, and how the very few people at those schools with sub par academic metrics have a hook like military, outstanding public service, URM, etc. I guess it all depends on how one defines "highest importance," but how truly "highest importance" was UG selectivity, not in 1970, but even in 2013, if more than a very nominal amount of matriculants at
@Goro's Really Top Schools came from not so top UGs, and those people do not need the hooks that people with crappy MCATs and GPAs need to break through?
I really think that's the flaw in that survey from 2013. No doubt a 4.0/520 from Harvard is more impressive than the same metrics from Kutztown, but that fact alone does not make UG selectivity a "highest importance" admission factor. If selectivity of UG is right up there with GPA and MCAT as a "highest importance" factor, how the hell does anyone, other than a token few with an outstanding hook, get into a Really Top School without it, let alone the vast numbers of people with great applications from less than stellar UGs that do so every freaking year?
Clearly it's really not of the "highest importance" since a lot of people break through every year without it -- many more than are successful at Really Top Schools who don't possess the other "highest importance" academic metrics of GPA and MCAT. How do you explain the divergence, if it's truly a "highest importance" academic metric in 2020? Your historical understanding of med school admissions from two generations ago doesn't really explain it.
You're really just saying what everyone already intuitively knows -- that, all things being equal, it's better to be coming from a prestigious, name brand school than a no-name one. But it's not 1970, and UG selectivity is not a "highest importance" admission factor, and that's why, all other things being equal, a 4.0/520 from Kutztown will beat out a 3.5/515 from Harvard, because Harvard vs. Kutztown is not a "highest importance" factor, whereas 4.0/520 vs. 3.5/515 is!!!

Today, Harvard vs. Kutztown is nothing more than a tiebreaker.
This is not to say that top UGs do not disproportionately produce a ton of successful candidates at Really Top Schools, because clearly they do. The question is whether, as the 2013 survey implies, this is because an ordinary candidate becomes a top candidate by virtue of attending a prestigious UG, or whether prestigious UGs just happen to attract a disproportionate number of superstar students who later become superstar candidates, because they were superstars going in, not because merely going to the school turned them into studs. I think it's the latter, and that it's a mistake to attribute a cause and effect rationale to the phenomenon. Again, if I am wrong, how is it possible that there aren't enough applicants with this "highest importance" admission factor, in addition to the other "highest importance" factors, to totally or nearly totally fill all of the seats at all of the Really Top Schools?