Great Minds Confabulate Like Small Minds
James Heckman won a Nobel Prize for his work on econometrics, statistics applied to economics. His latest work on education looks at the effects of programs on human capital.
In a recent Boston Review article on social mobility he highlights the results from two experiments in early childhood intervention that demonstrated significant benefits. Charles Murray was one of several comentors Murray noted these programs were small, having about 60 kids in each, and so are probably random outliers among the many different programs being conducted. After all, one really great teacher undoubtedly can make a difference in such a small sample, but really great teachers, by definition, aren't easy to replicate. Heckman, as is his wont, responded rather angrily that
As Einstein noted, "common sense is nothing more than a deposit of prejudices laid down in the mind before you reach eighteen." That a great econometrician could dismiss the clear selection bias in a couple of 60-kid studies selected out of hundreds (thousands?) highlights that no amount of education or intelligence can overcome one's prejudices, or overcome one's common sense.
Charles Murray mischaracterizes the quality of the evidence on the effectiveness of early childhood programs. In doing so he suggests that my evidence is highly selective. The effects reported for the programs I discuss survive batteries of rigorous testing procedures. They are conducted by independent analysts who did not perform or design the original experiments. The fact that samples are small works against finding any effects for the programs, much less the statistically significant and substantial effects that have been found.A small sample will have more trouble demonstrating statistically significant results--it has low 'power'--so Heckman is technically correct. But it's not as if these two programs were the only ones generated since 1962; these are really order statistics, not simple statistics. I see job seekers with fabulous backtests all the time, and cherry picking winning algorithms applied to a large class of rules is the most common problem.
As Einstein noted, "common sense is nothing more than a deposit of prejudices laid down in the mind before you reach eighteen." That a great econometrician could dismiss the clear selection bias in a couple of 60-kid studies selected out of hundreds (thousands?) highlights that no amount of education or intelligence can overcome one's prejudices, or overcome one's common sense.
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