Bryan Caplan asks whether increases in the graduation rate are really good news:
In the pure human capital model, rising graduation rates are good if they reflect increased learning. But they are not good if they reflect lower standards. For all its faults, the human capital model is no rationale for social promotion - handing out diplomas based on age rather than performance.
I think this is a bit of an oversimplification. It’s not implausible that the marginal low-achieving student would be better off with a diploma than failing to earn one, and his improved life prospects could very well be good news for the rest of us.
Still, it’s a reasonable question and it’s possible that the increased learning & social promotion explanations are not mutually exclusive.
Importantly, though, we have some evidence of the achievement of high school students from the NAEP long-term trend assessment. Those tests indicate that overall scores in math and reading have held steady (at least through 2008).
If more low-achieving students were persisting through high school only because of lower standards, shouldn’t that show up as lower NAEP scores among 17-year-olds?