Externalities dominate...

Check out this NYTimes Freakonomics blogpost on the recent NBER paper "Externalities in the Classroom: How Children Exposed to Domestic Violence Affect Everyone's Kids." I love the paper, hate the title.

The paper... is a rare quantitative glimpse into the impact that home life has on schools. I skimmed it; it isn't perfect, but it's credible. The basic conclusion:

we estimate that adding one more troubled boy peer to a classroom of 20 students reduces boys’ student test scores by nearly two percentile points (one-fifteenth of a standard deviation) and increases the probability that boys commit a disciplinary infraction by 17 percent (4.4 percentage points).

The title... makes me xenophobic. ("Are there kids like that in my brother's classes? How could we get rid of them?") It turns abused kids into damaged goods. It's a fair characterization of the evidence presented in the paper, but it's not the angle I would have taken.

In my mind, the real story is about the cost of broken relationships. It's more sad than surprising to see that really bad parenting can influence not just their own kids, but all the kids around them enough to show up on test scores and administrative records.

Key takeaway: People are remarkably interconnected. Externalities dominate any place where people are learning.

A PS -- I found the comments on the blog funny in a dark way. It's a mixed bag of snarky, offensive, shallow, and pompous. A few are insightful. I suppose we're all better for this kind of discussion, but the process is pretty messy.