Why Expanding New Mexico State Pre-K Won’t Help the Children Who Need Help the Most

As the inaugural cohort of 1,540 pre-K students completed their 14th year of school this past spring, the New Mexico’s Legislative Finance Committee (LFC) released a report on the state’s pre-K program, concluding that “prekindergarten remains a cost-effective way to improve student outcomes.” But the data the report cites does not support that conclusion. Indeed, the LFC makes three errors in interpreting the research it describes: mistaking correlation for causation, confusing statistical significance with real-world significance, and misusing the concept of cost-effectiveness.