Okay so a grad student advised me to ask potential grad schools about their attrition rates (since they're highly associated with student happiness in the department).
I know that it varies a lot from school to school, but are there departments that tend to have higher attrition rates than others? I'm intending to go into astrophysics, and my impression is that attrition rates for astrophysics are quite low compared to other fields (in fact, my school's astrophysics program has an attrition rate of 0% - it's very highly ranked on NRE for student outcomes). But the grad students here also say that the attrition rates for physics are much higher. Are the attrition rates for programs like biology also high? (I've heard nasty stories about disillusioned grad students, but all of them seem to have come from students in the biosciences).