# Category THE PATH FROM CAUSE TO EFFECT

## The Charter Conundrum

daisy: The lottery… isn’t that when people play and they win money?

Waiting for Superman, 2010

The release of Waiting for Superman, a documentary film that tells the story of applicants to charter schools in New York and California, intensified an already feverish debate over American education policy. Superman argues that charter schools offer the best hope for poor minority students who would otherwise remain at inner city public schools, where few excel and many drop out.

Charter schools are public schools that operate with considerably more autonomy than traditional American public schools...

## Fuzzy RD Is IV

In a regression rite of passage, social scientists around the world link student achievement to the average ability of their schoolmates. Such regressions reliably reveal a strong association between the performance of students and the achievement of their peers. Among all Boston exam school applicants, a regression of students’ seventh-grade math scores on the average fourth-grade scores of their seventh-grade classmates generates a coefficient of about one-quarter...

## Regressions Run

We start with regression estimates of the private school earnings advantage from models with no controls. The coefficient from a regression of log earnings (in 1995) on a dummy for private school attendance, with no other regressors (right-hand side variables) in the model, gives the raw difference in log earnings between those who attended a private school and everyone else (the chapter appendix explains why regression on a single dummy variable produces a difference in means across groups defined by the dummy). Not surprisingly, this raw gap, reported in the first column of Table 2.2. shows a substantial private school premium. Specifically, private school students are estimated to have earnings about 14% higher than the earnings of other students.

The numbers that appear in parentheses ...

## The Measure of Men: Controlling Ability

Here’s an easy work-around for the ability bias roadblock: collect information on A;- and use it as a control in regressions like equation (6.3). In an effort to tackle OVB in estimates of the returns to schooling, ’metrics master Zvi Griliches used IQ as an ability control.- Without IQ in the model, Griliches’ estimate of ps in a model controlling for potential experience is.068. Griliches’ estimated short regression schooling coefficient is well below Mincer’s estimate of about 11%, probably due to differences in samples and dependent variables (Griliches looked at effects on hourly wages instead of annual earnings). Importantly, the addition of an IQ control knocks Griliches’ estimate down to pl

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