Human Capital?

Following 2300 students over four years, we find that Study: Many college students not learning to think critically | McClatchy

Forty-five percent of students made no significant improvement in their critical thinking, reasoning or writing skills during the first two years of college, according to the study. After four years, 36 percent showed no significant gains in these so-called "higher order" thinking skills.

Note that this is not "compared to a control group who didn't go to college"; this is simply lack of improvement. In a control group, some would have developed the critical thinking skills being tested here, and some would not. To continue:

The study marks one of the first times a cohort of undergraduates has been followed over four years to examine whether they're learning specific skills. It provides a portrait of the complex set of factors, from the quality of secondary school preparation to the academic demands on campus, which determine learning. It comes amid President Barack Obama's call for more college graduates by 2020 and is likely to shine a spotlight on the quality of the education they receive.

Arum concluded that while students at highly selective schools made more gains than those at less selective schools, there are even greater disparities within institutions.
Students who majored in the traditional liberal arts — including the social sciences, humanities, natural sciences and mathematics — showed significantly greater gains over time than other students in critical thinking, complex reasoning and writing skills.
Students majoring in business, education, social work and communications showed the least gains in learning. However, the authors note that their findings don't preclude the possibility that such students "are developing subject-specific or occupationally relevant skills."

Hmm.....education students at the bottom. However you interpret it, that's not good news for future K-12 students. Those are tomorrow's teachers.
Or then again, maybe not.