Matt at Built On Facts spots an Inside Higher Ed article that I missed, showing that grad students at South Carolina get $9,500 a year, and uses it as a starting point to comment about grad school salaries:
The difficulty of living as a graduate student varies heavily on what you’re studying. Take at the law school model, for instance: you don’t get paid at all, and tuition is very expensive and not waived. But the upside to that is that you’re not in school very long, you can live comfortably on loans, and once out you can probably get a high-paying job which can pay down your debt fairly quickly. So lack of pay is not in and of itself the problem.
[...] In total though, the long duration of science (and physics especially) graduate education combined with the uncertainty of employment afterwards translates into salaries a lot better than the nine thousand dollars above. The graduate schools that I received offers from generally offered stipends a little north of $20,000 a year, with tuition waived.
This is exactly right. When I was a post-doc at Yale, the nascent grad student union tried to recruit one of the grad students in the lab, who pointed out that the average salary that the union was demanding would’ve been a $2,000 pay cut for him.
My standard advice for students trying to choose a graduate school in physics is “If they’re not offering to pay you, don’t go.” You’re not going to be paid well anywhere, but grad school is not so rewarding that you should do it for free, let alone pay for the privilege. You’re going to be there for a good while, generating data and publications for them– if they’re not going to pay you a living wage for that, find something else to do.
The extension to fields in which it takes a long time to graduate, the job prospects suck, and you get paid less than $9,500 a year is left as an exercise for the reader.