My alma-mater Augenblick, Palaich, and Associates has released the first round of achievement results for students in the Denver Preschool Program (DPP).  Sixty-four percent of third-graders reached proficient or advanced on third-grade state reading tests, compared to 58% of peers.

DPP is a sales-tax funded initiative launched in 2009.  I have been involved in DPP in one way or another since 2007, when the concept was first floated and the  immediate goal was to make a compelling case for a sales tax increase at the cusp of the recession.  Fortunately, voters took the bait, and DPP has helped over 25,000 kids attend preschool, according to their website.

DPP makes for a challenging evaluation subject because it is not a service program in its own right, but rather provides funds to help Denver children attend preschool.  APA’s evaluation work on DPP is not a program evaluation per-se, but rather an evaluation of the effects of preschool in general.  A further complication is that children do not fall neatly into “treatment” and “control” groups.  Some blurring in the treatment effect may occur because children who were not in DPP could theoretically have received preschool elsewhere (for example, if they recently moved to the district).  This would tend to underestimate the effect.

Having issued those caveats, my take is that the evidence DPP provides for the benefits of preschool is actually fairly impressive.  The program enrolls 70% of 4-year olds, which is close to a saturation rate for all children who are likely to enroll.  Further, the comparison group (those children who did not attend DPP) appear fairly similar to those who did in terms of income and ethnicity.  The reading results released today indicate that children who attend a single year of preschool have about a 10% greater chance of achieving proficiency in 3rd grade than those who did not (assuming the groups are similar).  This is a more robust finding than the recent Head Start impact study, which found that gains washed out by 3rd grade.

Denver’s results come on the heels of a report by the Federal Interagency Forum on Child and Family Statistics which confirmed that children who attended some early education had better performance in reading and math in kindergarten.

DPP now has an impressive and growing longitudinal database capable of tracking children throughout their K-12 experience, and it will be interesting to see how things play out as time goes on.