In some contexts, like business schools and law schools, tiers make sense since they are usually correlated with their graduates ability to find employment in the field after graduation. Graduates with JDs and MBAs may not be able to find suitable employment from lower ranked programs given the competitiveness of the field, declining job market, and greatly expanded enrollment of students in those programs. With medical school it’s a bit different since there are so few programs and an increasing need for / shortage of doctors. Because of this there really aren’t “low tier” programs in the traditional sense meaning someone is at risk of finding employment or not being able to move on to residency (note: this is for US graduates and not IMGs). Each program graduates a high percentage of their matriculating students who are then able to move on to residency and practice as a physician.
As far as what constitutes top, middle, and low tier, it’s largely subjective and based on ones enrollment. If you attend a program that is ranked #4 you might be inclined to say top tier is comprised of the top 5 or 10 programs. If you attend a school that is ranked #11 you might say top tier is up to 10, 15, or 20. TBH, having spent a lot time in areas where people are *obsessed* with rankings, I can honestly say I’ve yet to encounter someone who can clearly articulate the supposed benefits or substantial differences between one program and another.
