Friday, November 22, 2013

Free pre-school for low-income kids may be ineffective: A randomized controlled trial

Last week legislation was introduced in the Senate and House to create federally funded universal pre-k for 4-year-olds. ...

The rhetoric around the introduction of the legislation includes the by now entirely predictable and thoroughly misleading appeal to the overwhelming research evidence supporting such an investment. ...

Here I want to draw your attention to a newly released study of Tennessee’s Voluntary Pre-K Program (TN-VPK). TN‐VPK is a full day pre-k program for four‐year‐olds from low-income families. ...

The study, conducted by a stellar team of researchers at Vanderbilt, began in 2009. It is a randomized trial (the gold standard for evaluating program impacts) involving about 3,000 four-year-olds whose parents had applied for their admission to oversubscribed TN-VPK programs. A lottery was used to select those to whom an offer of admission was made. Those winning the lottery constitute the intervention group. Those losing the lottery constitute the control group. Only about a quarter of children in the control group found their way into other center-based programs such as Head Start or private pre-k, so the study compares groups that are very different in their levels of access to early childhood education. ...

...the group that experienced the Tennessee Voluntary State Pre-K Program performed somewhat less well on cognitive tasks at the end of first grade than the control group, even though ¾ of the children in the control group had no experience as four-year-olds in a center-based early childhood program.

What about social/emotional skills and dispositions as rated by teachers? The following figure presents those results, again at the end of first grade. None of the differences is statistically significant. Four of the seven signs are negative, meaning that the control group scored better than the pre-k group.

Finally, what about differences on routinely collected school records? Here the results are mixed. Participants in the TN-VPK were less likely to have been retained in kindergarten than non-participants (4% to 6%). In contrast, children served by TN-VPK were more likely to have received school-based special education services than children in the control group (14% to 9% for the full sample – reported results aren’t separated for the intensively studied sub sample). There were no statistically significant differences between the two groups on absences from school or disciplinary actions. ...

I see these findings as devastating for advocates of the expansion of state pre-k programs. This is the first large scale randomized trial of a present-day state pre-k program. Its methodology soundly trumps the quasi-experimental approaches that have heretofore been the only source of data on which to infer the impact of these programs. And its results align almost perfectly with those of the Head Start Impact Study, the only other large randomized trial that examines the longitudinal effects of having attended a public pre-k program.
--Grover J. "Russ" Whitehurst, Brookings Institute, on the case against publicly funding universal preschool. HT: Marginal Revolution