A just-released working paper by me, along with my co-authors William Gormley and Shirley Adelstein at Georgetown, considers, among other things, how Tulsa’s pre-K program affects middle-class children.  For middle-class children, we project that both the half-day and full-day versions of Tulsa’s pre-K programs have large future benefits in increased earnings, with these benefits exceeding costs. (We also find benefits exceeding costs for children from low-income families, but this is a more expected finding, as it is consistent with extensive previous research.)

The paper includes estimates of how Tulsa’s pre-K program affects test scores of students who are NOT eligible for a free or reduced-price lunch. We estimate that the average earnings of parents of these students are 135% of average earnings for the Tulsa metropolitan area. Therefore, this is by most definitions a “middle class” group of students.

We estimate that Tulsa’s half-day pre-K program, conducted for one school year at age 4, will increase the test scores of these middle-class students by 11 percentiles. This increase is over and above the increase that would occur without the program during that year, due to normal learning due to aging or participation in other programs.

What does an 11 percentile improvement mean? Consider a student who without Tulsa’s pre-K program would have scored at the 40^th percentile on some test at kindergarten entrance. This 40^th percentile performance means that the student’s test score level would have put them at a higher level than 40 percent of all entering kindergartners, and below 60 percent of all entering kindergartners.  An 11 percentile boost means that the student would instead score at the 51 percentile level – above 51 percent of all entering kindergartners. I think most parents would consider this a significant improvement.

We also find that a full-day pre-K program improves test scores of these middle-class students by 16 percentiles.  While doubling the pre-K day does not double student learning, it does bring about a significant increase.

Using estimates from Chetty et al, we project that these test score boosts will lead to considerable increases in future earnings. The 11 percentile boost is predicted to increase the present value of future adult earnings by over $16,000. The 16 percentile boost is predicted to increase the present value of future earnings by over $24,000.

As explained in the paper, these projected earnings increases assume that the increased skills will persist into adulthood to an extent similar to what is observed in Chetty et al’s study.  Although this projection requires this assumption, we present some evidence that this assumption is roughly accurate for previous high-quality preschool programs, such as the Perry Preschool program and the Chicago Child-Parent Center program.

These future earnings boosts have a present value that is many times these programs’ costs. The ratio of earnings benefits to costs for middle-class kids for the half-day program is 3.76. (The ratio for low-income kids is somewhat higher, at 4.01) The ratio of earnings benefits to costs for middle-class kids for the full-day program is 2.79. (For low-income kids, the full-day program has an earnings benefits to cost ratio of 3.09.) These “benefit-cost ratios” only consider one possible benefit of these programs, the effect on boosting future earnings. Benefits would be higher if we considered other benefits such as reduced crime or reduced need for special education costs.

The implication is that high-quality pre-K programs can produce net economic benefits by expanding their scope to include middle-class as well as low-income students.  Many middle-class parents will find it difficult to provide high-quality preschool with their own resources.  A high-quality publicly-supported preschool program can produce social benefits for the middle-class as well as for the poor.