Last month, the Biden campaign released a plan to implement universal preschool for all 3- and 4-year-olds to “cultivate the potential of young children” and “laying a strong foundation” for their academic success. While it may be well intentioned, the plan is based on critical errors in interpreting the research on the effects of preschool. If Joe Biden’s goal is to help America’s most vulnerable children, universal preschool is a costly mistake.
Proponents of universal preschool make an especially big mistake in misunderstanding a correlation between attending preschool and later school outcomes as evidence that preschool caused those outcomes. Correlation between two variables does not mean one caused the other. Two variables are often correlated because a third factor — not visible or accounted for in the data — is causing both. In the case of preschool, that third factor is crucial: parents.