Exploiting admission thresholds to the Bologna daycare system, we show using RDD that one additional daycare month at age 0–2 reduces IQ by 0.5% (4.7% of a s.d.) at age8–14 in a relatively affluent population. The magnitude of this negative effect increases with family income. Similar negative impacts are found for personality traits. These findings are consistent with the hypothesis from psychology that children in daycare experience fewer one-to-one interactions with adults, with negative effects in families where such interactions are of higher quality. We embed this hypothesis in a model that lends structure to our RDD.

Here is the forthcoming JPE article by Margherita Fort, Andrea Ichino and Giulio Zanella. And here are various ungated versions. (Do any of you have the links handy for other papers with similar results? They do exist.)

Quick quiz, we should:

a. Subsidize day care heavily

b. Not subsidize day care, or

c. Wait and see until more evidence is in.

Who is passing and failing this quiz? How about you?