The most passionate are the most obdurate.

A few years ago, a slew of states passed large, fairly comprehensive pre-K head-start type programs in a bid to improve education outcomes as well as to close the education gaps that exist from first grade, and which widen every grade following, between children of the poor and their better-off peers. Both desirable goals. However, pre-kindergarten programs, while popular for more than half a century as a solution, have rarely performed as anticipated. Multiple reviews of the grandaddy of pre-k programs, Head Start, have shown at best mixed results. The more rigorous the study, the smaller the measured results. A common finding of Head Start and similar pre-k programs, is that they yield a boost in assessed academic performance at First grade but all vestiges of that boost have disappeared by third-grade. There is no persistent effect.

It cannot be overlooked that these programs with vestigial outcomes are expensive.

Despite the lack of rigorous evidence, we keep trying to find how to rejigger the design or administration so that we get better results. Oklahoma and Tennessee have been a couple of second generation pioneers trying to rectify design failures in earlier programs and launching/re-launching new programs which it was hoped would yield positive results.

I am seeing a first large, rigorous review of the Tennessee effort for the first time.

From Effects of the Tennessee Prekindergarten Program on children’s achievement and behavior through third grade by Mark W.Lipsey, Dale C.Farran, Kelley Durkin. From the Abstract:

This report presents results of a randomized trial of a state prekindergarten program. Low-income children (N = 2990) applying to oversubscribed programs were randomly assigned to receive offers of admission or remain on a waiting list. Data from pre-k through 3rd grade were obtained from state education records; additional data were collected for a subset of children with parental consent (N = 1076). At the end of pre-k, pre-k participants in the consented subsample performed better than control children on a battery of achievement tests, with non-native English speakers and children scoring lowest at baseline showing the greatest gains. During the kindergarten year and thereafter, the control children caught up with the pre-k participants on those tests and generally surpassed them. Similar results appeared on the 3rd grade state achievement tests for the full randomized sample – pre-k participants did not perform as well as the control children. Teacher ratings of classroom behavior did not favor either group overall, though some negative treatment effects were seen in 1st and 2nd grade. There were differential positive pre-k effects for male and Black children on a few ratings and on attendance. Pre-k participants had lower retention rates in kindergarten that did not persist, and higher rates of school rule violations in later grades. Many pre-k participants received special education designations that remained through later years, creating higher rates than for control children. Issues raised by these findings and implications for pre-k policy are discussed.

Ouch. Their summary:

• This study of the Tennessee Voluntary Pre-K Program (VPK) is the first randomized control trial of a state pre-k program.


• Positive achievement effects at the end of pre-k reversed and began favoring the control children by 2nd and 3rd grade.

• VPK participants had more disciplinary infractions and special education placements by 3rd grade than control children.

• No effects of VPK were found on attendance or retention in the later grades.

Straight Talk on Evidence has a report here. They note:

In this report we discuss newly-published findings from a randomized controlled trial (RCT) of Tennessee’s voluntary prekindergarten (pre-k) program for low-income children (Lipsey, Farran, and Durkin 2018). We are highlighting this study for two reasons. First, the effectiveness of state and local pre-k programs is a topic of high policy importance. Approximately 28 percent of the nation’s four-year-olds are enrolled in pre-k programs funded by states, municipalities, or school districts—a number that has grown rapidly over time (Chaudry and Datta 2017)—and policy officials often tout pre-k as a powerful tool for closing school achievement gaps between minorities and whites and increasing earnings later in life (e.g., Executive Office of the President 2015).

Second, this study provides uniquely credible evidence on the topic. It is the first large RCT of a state-funded pre-k program, and one of only two such studies ever conducted of public preschool programs—the other being the national RCT of the federal Head Start program. Other studies of public or private preschool programs have had weaknesses that limit the reliability of their findings, such as lack of random assignment (e.g., Oklahoma universal pre-k, Chicago Child-Parent Centers) or small samples and imperfect randomization (e.g., Perry Preschool Project, Abecedarian Project).

Straight Talk's report has this disturbing addendum from the researchers:

In 2008 we worked closely with the Tennessee Department of Education to craft a strong experimental design that would assess the effectiveness of the TN Voluntary Pre-K program (TNVPK). Other than the Head Start Impact study, this would become the only randomized control study of a scaled-up public pre-k program.

Our initial results supported the immediate effectiveness of pre-k; children in the program performed better at the end of pre-k than control children, most of whom had stayed home. The press, the public, and our colleagues relished these findings. But ours was a longitudinal study and the third grade results told a different story. Not only was there fade out, but the pre-k children scored below the controls on the state achievement tests. Moreover, they had more disciplinary offenses and none of the positive effects on retention and special education that were anticipated.

Those findings were not welcome. So much so that it has been difficult to get the results published. Our first attempt was reviewed by pre-k advocates who had disparaged our findings when they first came out in a working paper – we know that because their reviews repeated word-for-word criticisms made in their prior blogs and commentary. We are grateful for an open-minded editor who allowed our recent paper summarizing the results of this study to be published (after, we should note, a very thorough peer review and 17 single-spaced pages of responses to questions raised by reviewers). We are also appreciative of the objective assessment and attention to detail represented in the Straight Talk review.

It is, of course, understandable that people are skeptical of results that do not confirm the prevailing wisdom, but the vitriol with which our work has been greeted is beyond mere scientific concern. Social science research can only be helpful to policy makers if it presents findings openly and objectively, even when unwelcome.

We share with our colleagues a commitment to the goal of providing a better life for poor children. Blind commitment to one avenue for attaining that goal, however, is unnecessarily limiting. If pre-k is not working as hoped and intended, we need to roll up our sleeves and figure out what will work, with solid research to guide that effort.

Rhetoric, emotion and advocacy play too dominant a role in our public discourse. No one is bettered by suppressing evidence we might dislike because it contradicts our priors. We only improve by tackling the world as it is rather than as we might wish it to be.