Is the Link Between Day Care and Misbehavior Overstated? 

Whether center-based child care affects kids’ misbehavior is a long-running controversy, both in the academic literature and in the “Mommy Wars” writ large. 

From the research, the message has been a modest note of caution. Overall effects are often small and hard to measure, but at least some day care arrangements seem to worsen some kids’ outcomes. Bad results seem most likely, unsurprisingly, when the child care programs in question are lower-quality, or when the families in question can give particularly high-quality care if the child stays home. 

To arrive at these conclusions, some studies have simply looked for correlations between kids’ child care arrangements and their actions, while controlling for confounding factors like parental education. Others, such as an often-cited study of Quebec, Canada, have exploited “natural experiments” where day care abruptly became more widely available.

A new study published in Child Development, however, takes a different approach and finds virtually no sign of any effect of center-based child care on “externalizing” behavior problems such as hitting or bullying. It’s a worthy contribution to the literature, though it doesn’t simply override everything that came earlier. The new study’s approach, rarely used before, has limitations of its own. 

The new research looks for “within-child” correlations between problem behaviors and hours spent in center-based child care. In other words: When a child starts spending more or less time in a day care program, does his behavior change too, as measured by teacher or parent reports? The study analyzes two datasets each from the U.S. and Canada, plus one each from Germany, the Netherlands, and Norway, containing about 10,000 toddlers and preschoolers in total. 

Because each child is basically serving as his own control group, this approach eliminates some concerns with purely “observational” studies that check to see if kids who spend more time in center-based care behave worse than their peers. In those studies, it’s possible that the kids put in a day care program for long periods are simply different from other kids, in ways that the researchers were not able to control for. Eliminating that worry is a huge point in the new study’s favor. 

But the new approach also represents a narrow way of looking at the issue. It is incapable of detecting longer-term effects, as it assumes a very direct relationship between how much time a child is currently spending in center-based care and whether he’s currently exhibiting problematic behaviors; it excludes kids who never attended day care at all (owing to the focus on within-child changes in day care hours); and it doesn’t rule out the possibility that changes in kids’ child care hours are correlated with other changes that affect behavior. Measurement error is also a concern, as both child care hours and misbehavior ratings are collected via surveys in these datasets. This study certainly shouldn’t prompt us to disregard the more rigorous previous studies that relied on natural experiments. 

Nonetheless, it’s worth stressing how resoundingly the study fails to find ill effects of center-based care. None of the seven datasets showed statistically significant within-child effects.¹ There was little sign that effects are worse for kids from better-off families (which might be expected if those families provide better care at home). Combining all seven datasets into a meta-analysis, the within-child correlation between hours in center-based care and externalizing problems was, astoundingly, 0.00. 

On top of that, the authors ran a supplementary analysis that at least partially addresses concerns about effects that take hold gradually over time. In this model, they measured cumulative rather than current use of day care. (As they put it, if a kid spent 30 hours a week in child care in each of three different time periods when a dataset was collected, the cumulative load would be 30 in the first time period, 60 in the second, and 90 in the third.) This, too, failed to detect any ill effects. 

Again, those keeping tabs on the literature or making their own child-care decisions should not assume this new research simply sweeps all other findings away—and the authors themselves are frank about the limitations of their work. Most important, it only tells us the short-term story. But this is a careful analysis of a whole lot of data, and it suggests center-based child care might have less of an effect on misbehavior than some earlier work shows. 

Robert VerBruggen is an IFS research fellow and a fellow at the Manhattan Institute.

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1. In addition to the “fixed effects” models that zero in on within-child effects, the authors run “random effects” models for comparison that include between-child effects. Even in these weaker models, only two of the datasets show a correlation between center-based daycare time and externalizing problems, one of which is significant only at the 10% level.