September 2010
The House of Representatives has passed what I like
to think of as Larry’s Law. The official title of
this legislation is
“Fulfilling the potential of women in academic science and engineering,” but
nothing did more to empower its advocates than the controversy over a speech by
Lawrence H. Summers
when he was president of
Harvard.
This proposed law, if passed by the Senate, would require the White House
science adviser to oversee regular “workshops to enhance gender equity.” At the
workshops, to be attended by researchers who receive federal money and by the
heads of science and engineering departments at universities, participants would
be given before-and-after “attitudinal surveys” and would take part in
“interactive discussions or other activities that increase the awareness of the
existence of gender bias.”
I’m all in favor of women
fulfilling their potential in science, but I feel compelled, at the
risk of being shipped off to one of these workshops, to ask a couple of questions:
Each of these questions is complicated enough to warrant a column, so I’ll take
them one at a time, starting this week with the issue of sex differences.
When
Dr. Summers raised the issue to fellow economists and other researchers at a conference
in 2005, his hypothesis was caricatured in the press as a revival of the old
notion that “girls can’t do math.” But Dr. Summers said no such thing. He
acknowledged that there were many talented female scientists and discussed ways
to eliminate the social barriers they faced.
Yet
even if all these social factors were eliminated, he hypothesized, the science
faculty composition at an elite school like Harvard might still be skewed by a
biological factor: the greater variability observed among men in intelligence
test scores and various traits. Men and women might, on average, have equal
mathematical ability, but there could still be disproportionately more men with
very low or very high scores.
These extremes often don’t matter much because relatively few people are
involved, leaving the bulk of men and women clustered around the middle. But a
tenured physicist at a leading university, Dr. Summers suggested, might well
need skills and traits found in only one person in 10,000: the top 0.01 percent
of the population, a tiny group that would presumably include more men because
it’s at the extreme right tail of the distribution curve.
“I
would like nothing better than to be proved wrong,” Dr. Summers told the
economists, expressing the hope that gender imbalances could be rectified simply
by eliminating social barriers. But he added, “My guess is that there are some
very deep forces here that are going to be with us for a long time.”
Dr.
Summers was pilloried for even suggesting the idea, and the critics took up his
challenge to refute the hypothesis.
Some have claimed he was proved wrong by recent reports of girls closing the gender gap on
math scores in the United States and other countries. But even if those reports
(which
have been disputed)
are accurate, they involve closing the gap only for average math scores — not
for the extreme scores that Dr. Summers was discussing.
Some scientists and advocates for gender equity have argued that the remaining
gender gap in extreme scores is rapidly shrinking and will disappear. It was
called “largely an artifact of changeable sociocultural factors” last year by
two researchers at the
University of Wisconsin,
Janet S. Hyde and Janet E. Mertz.
They noted evidence of
the gap narrowing and concluded, “Thus, there is every reason to
believe that it will continue to narrow in the future.”
But
some of the evidence for the disappearing gender gap involved standardized tests
that aren’t sufficiently difficult to make fine distinctions among the brighter
students. These tests, like the annual ones required in American public schools,
are limited by what’s called the ceiling effect: If you’re measuring people in a
room with a six-foot ceiling, you can’t distinguish among the ones taller than
six feet.
Now
a team of
psychologists
at
Duke University
has looked at the results of tests with more headroom. In
an article in a
forthcoming issue of the journal Intelligence, they analyze the test
scores of students in the United States who took college admissions tests while
they were still in the seventh grade. As part of an annual talent search since
1981, the SAT and ACT tests have been given to more than 1.6 million gifted
seventh graders, with roughly equal numbers of boys and girls participating.
The
Duke researchers — Jonathan Wai, Megan Cacchio, Martha Putallaz and Matthew C.
Makel — focused on the extreme right tail of the distribution curve: people
ranking in the top 0.01 percent of the general population, which for a seventh
grader means scoring above 700 on the SAT math test. In the early 1980s, there
were 13 boys for every girl in that group, but by 1991 the gender gap had
narrowed to four to one, presumably because of sociocultural factors like
encouragement and instruction in math offered to girls.
Since then, however, the math gender gap hasn’t narrowed, despite the continuing
programs to encourage girls. The Duke researchers report that there are still
four boys for every girl at the extreme right tail of the scores for the SAT
math test. The boy-girl ratio has also remained fairly constant, at about three
to one, at the right tail of the ACT tests of both math and science reasoning.
Among the 19 students who got a perfect score on the ACT science test in the
past two decades, 18 were boys.
Meanwhile, the seventh-grade girls outnumbered the boys at the right tail of
tests measuring verbal reasoning and writing ability. The Duke researchers
report in Intelligence, “Our data clearly show that there are sex differences in
cognitive abilities in the extreme right tail, with some favoring males and some
favoring females.”
The
researchers say it’s impossible to predict how long these math and science
gender gaps will last. But given the gaps’ stability for two decades, the
researchers conclude, “Thus, sex differences in abilities in the extreme right
tail should not be dismissed as no longer part of the explanation for the dearth
of women in math-intensive fields of science.”
Other studies
have shown that these differences in extreme test scores correlate with later
achievements in science and academia. Even when you consider only members of an
elite group like the top percentile of the seventh graders on the SAT math test,
someone at the 99.9 level is more likely than someone at the 99.1 level to get a
doctorate in science or to win tenure at a top university.
Of
course, a high score on a test is hardly the only factor important for a
successful career in science, and no one claims that the right-tail disparity is
the sole reason for the relatively low number of female professors in
math-oriented sciences. There are other potentially more important explanations,
both biological and cultural, including possible social bias against women.
But
before we accept Congress’s proclamation of bias, before we start re-educating
scientists at workshops, it’s worth taking a hard look at the evidence of bias
against female scientists. That will be the subject of another column.
New York Times, June 7, 2010.
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