What does the research say?The previous tables and descriptions refer to 13 separate studies (including 3 similar studies of district programs and two similar studies of statewide programs in Oklahoma and Georgia). Of these 13, six report enduring and meaningful impacts beyond the pre-k pre-k year, and three do not report findings beyond the pre-k year.
It would be easy for someone without the training to carefully evaluate these studies or someone with a strong motive to advocate for the expansion of publicly funded pre-k to summarize this research by saying that the preponderance of evidence supports universal pre-k for four-year-olds. After all, of the 10 studies I’ve reviewed that have long-term follow-up, 60 percent report substantive positive outcomes.[xiii] Libby Doggett, the Obama administration’s point person on Preschool for All, has been singing exactly this song at every opportunity:
You have to look at the preponderance of the evidence. Better high school graduation rates, social and emotional stability, less crime and other results speak for themselves.[xiv]But results do not speak for themselves. Rather, it is the combination of results and the research designs that produce them that do the speaking. And some of the combinations speak a lot louder than others.
Not one of the studies that has suggested long-term positive impacts of center-based early childhood programs has been based on a well-implemented and appropriately analyzed randomized trial, and nearly all have serious limitations in external validity. In contrast, the only two studies in the list with both high internal and external validity (Head Start Impact and Tennessee) find null or negative impacts, and all of the studies that point to very small, null, or negative effects have high external validity. In general, a finding of meaningful long-term outcomes of an early childhood intervention is more likely when the program is old, or small, or a multi-year intervention, and evaluated with something other than a well-implemented RCT. In contrast, as the program being evaluated becomes closer to universal pre-k for four-year-olds and the evaluation design is an RCT, the outcomes beyond the pre-k year diminish to nothing.I conclude that the best available evidence raises serious doubts that a large public investment in the expansion of pre-k for four-year-olds will have the long-term effects that advocates tout.This doesn’t mean that we ought not to spend public money to help families with limited financial resources access good childcare for their young children. After all, we spend tax dollars on national parks, symphony orchestras, and Amtrak because they make the lives of those who use them better today. Why not childcare?It does mean that we need public debate that recognizes the mixed nature of the research findings rather than a rush to judgment based on one-sided and misleading appeals to the preponderance of the evidence....
Tuesday, September 23, 2014
Liberal Brookings Institute Concludes "Best Available Evidence" Shows Pre-K Doesn't Provide Benefits Touted by Proponents
Earlier this year the liberal Brookings Institute did a report evaluating tpre-K studies and reached the conclusion that most suffered from serious methodology flaws and concluded that the evidence was not there that pre-K offered the benefits suggested by proponents. Below is the conclusion from that report:
To read the entire Brookings report, click here.