For both Medical Schools and residencies, do you think this has to do with better students, better advising, better curriculum, or just students learning how to game these tests better (ie studying the test not the material)?
Personally I think it's part of a global change in student selection processes, which has happened along the whole chain from competitive colleges, to med schools, to competitive residency.
It used to be that academic metrics were a check-box to make sure you had the necessary brainpower, and what really made people desirable was elsewhere in the app. For example, Yale college in the 1980s had median Math+Verbal SATs of 1340 (
top 10% at the time). But, one generation later, shoots up to 1510 (
top 0.5% now).
Similar happened with medical schools, with the top med schools holding MCAT medians of around 33 (
top 10%) a decade ago, now up to 519+ (
top 1%). Clearly, there's been a change in the zeitgeist of competitive student selection to very heavily emphasize standardized scores.
As to why this happened / continues to happen, I think it's due to the rise of the internet and "common application" systems. Gone are the days when you applied to college or med school based on what nearby options had solid reputations, and when each one had its own application limiting your numbers of apps. Instead you get today's system, where high achieving students strive for top 1% test scores and then all apply all over the country via common application to the same ~20-25 places that hold the highest score ranges and rankings.
With schools receiving a huge increase in application numbers, and suddenly fighting for elite status based on their test scores and rankings, it's no wonder that colleges and medical schools have started using absurdly high standardized score ranges as a filter and major criteria. Residency, I expect, is seeing some of the same phenomenon - a lot more applicants, and the use of test scores to decide who is the cream of the crop that deserves closer inspection.
The phenomenon also isn't restricted to scores and grades. Part of the NRMP data set is the number of "posters, publications and abstracts" on the residency application. In 2010, the mean number for a successful neurosurgery resident was
7.8. Eight years later it is now two-and-a-half times that, at
18.3! It's a positive feedback ratrace where every year the norm gets progressively more ridiculous, in extra curriculars as well as test scores.
Overall it's a very different world for students at all levels than it was a decade or two ago, and I certainly don't envy the hell that our children will have to go through if they want to be in the running for "top 20" or "competitive specialty" or whatever after another generation of this trend.