Tuesday, May 9, 2017

The impact of lead on behavior: school suspensions and juvenile detention

Using a unique dataset linking preschool blood lead levels (BLLs),
birth, school, and detention data for 120,000 children born 1990-2004
in Rhode Island, this study estimates the impact of lead on behavior:  school
suspensions and juvenile detention.  The authors develop two instrumental
variables approaches to deal with potential confounding from omitted
variables and measurement error in lead.  The first leverages the
fact that we have multiple noisy measures for each child.  The second
exploits very local, within neighborhood, variation in lead exposure
that derives from road proximity and the de-leading of gasoline.

Both methods indicate that OLS (ordinary least squares)
considerably understates the negative effects of lead,
suggesting that measurement error is more important
than bias from omitted variables.  A one-unit increase in lead
increased the probability of suspension from school by 6.4-9.3
percent and the probability of detention by 27-74 percent, though the
latter applies only to boys.

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