Arnold Kling notes that we display A Preference for Ignorance:
In the fields of health care, education, and assistance to poor countries, we rarely measure value properly. It seems as though we prefer to be ignorant about what succeeds and what fails. We know shockingly little about the cost-effectiveness of very expensive programs.
MIT’s Abhijit Vinayak Banerjee points out an example:
The cheapest strategy for getting children to spend more time in school, by some distance, turns out to be giving them deworming medicine so that they are sick less often. The cost, by this method, of getting one more child to attend primary school for a year is $3.25. The most expensive strategy among those that are frequently recommended (for example by the World Bank, which also recommends deworming) is a conditional cash-transfer program, such as Progresa in Mexico, where the mother gets extra welfare payments if her children go to school. This costs about $6,000 per additional child per year, mainly because most of the mothers who benefit from it would have sent their children to school even if there were no such incentive. This is a difference of more than 1,800 times.
We’re similarly ignorant about schooling our own children (and young adults):
We seem to be most determined to remain ignorant in the field of education. The testing in No Child Left Behind is based on observational studies, rather than experiments. That is, we look at school quality solely in terms of outcomes. We label a school as good or bad without having any idea whether the school actually adds value.Imagine what might happen if one were to run a controlled experiment, pooling a group of students and randomly assigning them to different schools. Would the “good” suburban school really do better than the “failing” urban school, once the population of students is similar?
I suspect that controlled experiments in education would show shockingly little value added. That is, if you were to randomly assign students to schools, the children of good parents would do well regardless of where you send them, and conversely.
I suspect that controlled experiments in higher education would also show little value added. Everyone can cite the differences in earnings between college graduates and non-graduates, but those differences do not come from controlled experiments. What if you were to undertake a randomized trial, in which a cross section of high-school graduates is sent to college and then compared with a similar cross-section that is not sent to college? My guess is that the earnings differences will not be so large.