I've never heard of this. Can you give me (as much as possible,) some examples of this difference?
Only anecdote I'm afraid. I've had several IM, SDN Chat, and in person conversations where the person I'm talking to is convinced that their MD/PhD program is less competitive than their MD program. This has always been people who are at or have gone to lower tier allopathic schools with unfunded MD/PhD programs. They usually tell me that the GPA/MCAT of those MD/PhDs are the same if not lower than the MD only students, but again, it's only anecdote and I don't know whether that's reliable information.
There are two problems with me coming to any solid conclusion on this issue. The first is, I have no data (Maebea can you help?) on this. Part of the problem is that the unfunded MD/PhD programs tend not to be in the inner circle of the MSTPs that all share information with each other. The only thing I know for sure is that unfunded positions have a much higher program dropout rate (at least here at Penn when they used to have unfunded spots).
The other issue is that there's a confounding variable. To generalize wildly, the top USNews research ranking MD programs are the MSTP schools. the next tier down are the fully-funded MD/PhD programs. For the most part, you have to get to lower tier allopathic schools before you see wholly unfunded MD/PhD programs. Are the matriculant numbers lower based on the tier/prestige of the school or are they lower based on funding? To answer that question I'd want to look at two pools of programs.
1) Higher tier MD programs with unfunded MD/PhD programs
2) Lower tier MD programs with fully funded MD/PhD programs
That to me would answer the question of what is really driving the competitiveness. The truth is, it's probably a combination of both, though one could reasonably suspect that just not funded vs. funded drives a good amount of competition. I mean, shouldn't ~$250,000 do that?
😉