What ultimately matters to preschool quality is what goes on in the classroom, between teacher and child.  This makes intuitive sense, and is also backed by research. Several studies indicate that preschool achievement gains are higher if more classroom time is devoted to teachers interacting with children individually, particularly with high quality questions and feedback that develops thinking skills.  In the preschool research field, such improvements are referred to as improvements in “process quality” in that they improve the process of what goes on in the classroom.

In chapter 5 of Investing in Kids , I use these research results to estimate the benefits of improvements in preschool “process quality”. I consider what would happen if a preschool classroom, on these process quality measures, changed from the median classroom to a classroom that would be ranked in the 84^th percentile. That is, the classroom would change from being better than half of all preschool classrooms, to being better than 84% of all preschool classrooms. (This particular improvement was considered because it is equal to what statisticians call a “one standard deviation” improvement.) The resulting test score improvements were used to project future economic development benefits for the local economy.

These calculations suggest that such process quality improvements would increase the present value of state residents’ earnings – which is called “economic development benefits” in my book – by 29% to 47% of the typical cost of preschool programs. Therefore, such quality improvements would have economic development benefits exceeding costs as long as making such process quality improvements did not increase per student costs of preschool programs by more than 29% to 47%.

It seems likely that good preschool management could attain such process quality improvements at a cost increase of less than 29%.  Presumably such process quality improvements require more attention to teacher training and teacher hiring, and more expert interventions by preschool management. Although this would cost something, it seems unlikely that it would raise preschool costs as much as 29%.

In short, preschool process quality pays off for the local economy, and by quite a bit compared to the costs of quality.