Before we embark on universal preschool, we should look at the results from universal kindergarten. According to Elizabeth U. Cascio, assistant professor of economics at Dartmouth College, the gains were far short of expectations:

My results indicate that state funding of universal kindergarten had no discernible impact on many of the long-term outcomes desired by policymakers, including grade retention, public assistance receipt, employment, and earnings. White children were 2.5 percent less likely to be high school dropouts and 22 percent less likely to be incarcerated or otherwise institutionalized as adults following state funding initiatives, but no other effects could be discerned. Also, I find no positive effects for African Americans, despite comparable increases in their enrollment in public kindergartens after implementation of the initiatives. These findings suggest that even large investments in universal early-childhood education programs do not necessarily yield clear benefits, especially for more disadvantaged students.

The full post can be found here.

What studies like this ignore is that it isn’t rigorous data politicians base their decisions on: its the next election. And programs like universal kindergarten and today’s universal preschool efforts, while they do little to actually improve education, do improve the wallets of a very powerful lobbyists group - the teachers union. And when it comes to policy, that is what matters most.