GPA, PGRE, and Top 20 Admissions

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GPA, PGRE, and Top 20 Admissions

Post by DiracMan » Fri Jan 04, 2013 4:08 am

I have been curious for a while about just how "shallow" the physics admissions process really is. More specifically, I wanted to learn how well you can predict whether someone will get into a well-ranked program based strictly on their GPA and physics GRE score. So, using the phenomenal database this website has accumulated, I set about to find the (statistical) answer using all the applicant profiles from 2011 and 2012 (I was originally just going to do 2012, but I got to the end and was not convinced the sample size was large enough to be meaningful).

First some boring notes about methodology and disclaimers:
1. Due to a combination of selfishness and laziness, this analysis only considers domestic applicants.
2. I only considered applicants with a clear physics/astronomy focus. If an applicant was focused primarily on earth science/engineering/etc., I did not count them toward anything.
3. I have not controlled for gender/minority status.
4. There is potentially a large systematic error with my approach: an applicant with a fantastic GPA and PGRE score is very likely to have good research experience, great recommendation letters, personal statement writing skills, etc. Controlling for these factors would be difficult, and is not really in the spirit of the study. The point is to assess the predictive power of GPA together with PGRE score. How exactly you interpret that is up to you.
5. I define a "successful application experience," or SAE, as getting into any school ranked in the top 20 physics programs according to the US News list. Anyone getting into a top 20 program is said to have "had an SAE."
6. I define a "strong applicant," or SA, as anyone with an overall GPA at or above a 3.7 and a PGRE score at or above an 800 (if anyone repeated this for international applicants the PGRE number would obviously have to be higher). I observed surprisingly little variation between "major GPA" and "overall GPA" for most applicants, but this is something you could control for pretty easily if so inclined.

And, after reducing the 2011 and 2012 data, here are the results:

Total # of SAE: 80
# of SAE among those with PGRE at or above 800 and GPA at or above 3.7: 43
# of SAE among those with PGRE below 800 and GPA at or above 3.7: 24
# of SAE among those with PGRE above 800 and GPA below 3.7: 9
# of SAE among those with PGRE below 800 and GPA below 3.7: 4

Note that over half of SAEs went to SA-level profiles.

I also analyzed the results of all SA profiles:

Total # of SA Profiles: 55
# of SA Profiles with an SAE: 45

It is this last statistic I find most jarring. Almost every SA-level applicant got into a top 20 program. An anecdotal survey of the ten unlucky SA-level profiles tended to reveal other significant flaws (no research at all, been out of school for 15+ years, etc.). Most (virtually all) admissions councilors I have spoken with like to say that they give recommendation letters greater weight than GPA and PGRE score, but I find that somewhat hard to believe when confronted with a correlation coefficient above 0.8. You would have to believe that recommendation letter quality tracks extremely closely with GPA/PGRE to accept that argument. I tend to buy into the quasi-common wisdom that personal statements matter comparatively little, but I know of no way to test this.

It would be interesting if someone wanted to tweak the SAE/SA parameters and rerun the analysis. I conjecture that the results would change fairly little, since 3.7 is a pretty good GPA by almost any measure and an 800 is generally great for a domestic (I suspect anything above an 850 is overkill unless you are only interested in Stanford or Berkeley).

I do not know how interested the rest of the PhysicsGRE community is in my games, but here you go. :)

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Re: GPA, PGRE, and Top 20 Admissions

Post by Etranger » Fri Jan 04, 2013 8:49 am

Did you include international students who studied in the USA? I'm not sure if this is just for undergrad, or if this works the same way for those who did some grad school in the States too, but apparently they are evaluated like domestic applicants. Perhaps exceptions would be schools low on funding, like the ones in CA. (from what I hear)

How long did this take you?

I can think of a way to test for the weight placed on the SoP, but it's not ethical by my standards. That would involve "creating" applications from scratch, sending them, and then collecting the results. Now, I'm willing to bet that universities/colleges have indulged in some unethical activities themselves (all this marketing about how THIS college will change your life, reporting fake/doctored data to rankings, etc), but I don't know if it's a line I'd be willing to cross.

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Re: GPA, PGRE, and Top 20 Admissions

Post by Throwaway1 » Sun Jan 13, 2013 11:40 pm

Honestly, those findings do make a great deal of sense to me. Some speculation:

PGRE matters, but a solid GPA carries more weight (huge gap between 9 and 24 there). At the very least, those numbers suggest that a stronger GPA easily overshadows a lower performance on a single test (perhaps with a combination of other relevant factors). The PGRE is not the end all be all since a substantial number of applicants with GPA > 3.7 but ?<PGRE<800 are SAE. That's encouraging news for those who have stronger GPAs but are worried about the role of their PGRE score.

Something important about the applicant "rescues" the SAE with PGRE below 800 and GPA below 3.7. Unusually strong research background? I don't want to say minority status or gender, but it would be interesting to see who is getting admitted to top 20 with those stats.

There is certainly a need for caution when attempting to decipher the role of letters of recommendation. Letters matter a lot, but there is probably a variance in the weight admission boards give to letters. I would be tempted to say that in the circumstance that there is an applicant below 800 and 3.7 GPA, something else needs to stand out. Something big. Perhaps at that point, letters are treated with more weight to look for other factors to measure success and aptitude. Truthfully, letters matter in differentiating aptitude to work in a professional research environment and as such, are fairly important.

I am wary when I read applicant profiles that say, "2 years of research and no publication/no publication in progress." Now that can be tricky to interpret, but it's a good example to emphasize. Sometimes, some research projects just don't work out. That is not necessarily the fault of the student. But sometimes, students join a lab, work for two years, but maintain a "social" or "peripheral" role in their lab. Those students do enough work to get a decent letter of recommendation and respect from their advisor, but don't really do much else other than what their advisor tells them to do. Sometimes, the people that just "follow orders" in a lab get enough results to even have their name on a paper. Then there are people that join a lab and "take control." They are motivated in a different sort of way. Those students don't just want to follow orders, get results, and go home (and not really think much about lab thereafter), but want to independently interact with their assigned projects, engage deeply with the scientific literature, and even design their own solutions to solve a scientific problem. A strong letter of recommendation, personal statement, or optional research statement (found on some applications) will easily pick out the difference between those who show a great deal of investment in their research vs. those who are just there to run the experiments someone else designed and get some results: a science technician, if you will. That will be the difference between a good/great letter of recommendation vs. an outstanding letter.
Last edited by Throwaway1 on Mon Jan 14, 2013 12:51 am, edited 1 time in total.

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Re: GPA, PGRE, and Top 20 Admissions

Post by bfollinprm » Mon Jan 14, 2013 12:48 am

I find this encouraging to someone in their first or second year in undergrad. It means that with diligence you can near-guarantee yourself admission to a top-20 physics program by working hard on keeping a good GPA and studying hard for the PGRE. I'm also interested, however, in what kind of applicants who did not have strong PGRE scores or high GPAs got into top-20 schools.

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Re: GPA, PGRE, and Top 20 Admissions

Post by actrask » Sat Jul 06, 2013 4:06 am

For anyone interested, I counted up the 2013 profiles in the same way DiracMan did:

Total # of SAE: 42
# of SAE among those with PGRE at or above 800 and GPA at or above 3.7: 24
# of SAE among those with PGRE below 800 and GPA at or above 3.7: 13
# of SAE among those with PGRE above 800 and GPA below 3.7: 3
# of SAE among those with PGRE below 800 and GPA below 3.7: 2

Total # of SA Profiles: 28
# of SA Profiles with an SAE: 24

So very similar results. Something that is perhaps important to note is that several of the 13 with PGRE below 800/GPA above 3.7 had received a score of 790.

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