Actually, you can. If you look at the percentiles and approximate an SD, including the level of skew to the distribution, you can see whether or not a given school seems to accept applicants from a wide range or not. Additionally, looking at %s of matriculants w/ a given set of ECs (i.e., research, clinical, volunteer) gives you some indication as well. These are what the spreadsheet uses to approximate just how important ECs are. The methodology used is obviously imperfect (how could it not be?) but for a basic idea of where you might want to shoot as far as apps go, I believe it is at least an useful tool for what the OP asked there.
Are you referring to this 'Chance Me' spreadsheet that was floating around? When plugging in my numbers into that sheet, I was given a 90 percent chance of an interview at some of the top schools. In my opinion, that's completely off base for ANY school.
Additionally, no statistical process can take into account the self selection that occurs. If person A with great extracurriculars but a 32 MCAT doesn't apply to Harvard, you're not going to get an accurate picture of the entire range. Same with the person with a 40 MCAT who doesn't apply to their local schools.
As for the bolded portion, you assume that matriculants are a representative sample of the accepted pool. Especially at 'lower-tier' schools, that's inaccurate. Plenty of extremely qualified candidates get into those schools, and also get into top 10 schools, and decline the acceptances at the 'lower-tier' schools. That's going to throw off that analysis. Furthermore, you're trying to QUANTIFY stuff like a letter of recommendation from a volunteer supervisor. Doesn't that strike you as a little ridiculous?
Finally, how does one factor in the correlation between a good MCAT/GPA and ECs? People who have better grades (if you remove the outliers who don't study much and get good grades) generally have put more effort into their medical school preparation as a whole. That means they usually put more time into ECs to buff up their application.
What does that above paragraph mean? Well, it means that when Harvard accepts a class that has an average MCAT score of 36, the accepted most likely ALSO have strong extracurriculars. How do you figure out if Harvard actually emphasizes one or the other more than another medical school, or if it's just the natural correlation between the two?
Without accounting for the factors mentioned here, I don't think any sort of quantification of a process where SO many steps involve human reasoning is possible. Maybe you can compare between schools that share a similar perception to pre-med students. For example, comparing statistics/ECs between Stanford and Harvard might work. Comparing them across all medical schools? Nay.
EDIT: The one thing that really grated me on that spreadsheet was the idea that you tried to give points for things like 'Does your extracurricular activity show you have a good work ethic?' How do you expect a student who's filling in blanks on that thing to have the perspective of a committee member when they go through it?
And what information did you use to calculate the impact of a letter of recommendation from a research supervisor? Or from a volunteer supervisor? Does anyone even publish information regarding from where students got their letters of recommendation? How about the schools that say letters of recommendation from academic faculty >> anything else?