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Addendum: “Yields” and “Parity Indices” for Top Astronomical Institutions

By Meg Urry and Valerie Kuck

January 2002


HOW DOES astronomy compare to physics and chemistry in the advancement of women? In
the accompanying article Kuck finds that top physics departments graduate a smaller
fraction of women than are in the graduate student pool, yet hire a slightly higher fraction
than in the relevant Ph.D. pool. In contrast, top chemistry departments graduate relatively
more women yet hire far fewer women than the percentage in the Ph.D. pool. Statistics for astronomy
(Urry, STATUS, January 2001) suggest that the top ranked astronomy departments
are as likely, and possibly more likely, to hire a significant percentage of female astronomers (relative yields of
graduate schools were not investigated in that work), but an astronomy study comparable
to Kuck’s analysis of chemistry and physics has not previously been done.

Here we look at the top astronomy departments and evaluate the same
statistics as in Kuck’s article, namely Ph.D. completion rates of male and female graduate
students in a 5-year period, 1993-1997; the corresponding number of first-year graduate
students (1988-1992); and the number of women recently hired as assistant professors
at the top astronomical institutions1.

We caution that the results have large statistical uncertainties, there being far
fewer astronomers in the U.S. than either chemists or physicists. Furthermore, the
simplistic analysis attempted here is distorted by the influx of graduates from
physics (and elsewhere), and by the incredible growth of astronomy in the 1990s. (As just
one example of this growth, there were more Ph.D.s in 1994-1998 than graduate
students in 1988-1992.) Still, a few straightforward conclusions are possible.

The yield of Ph.D.s relative to entering graduate students varies tremendously for
individual top-10 departments, ranging from 43% to 200% for women and
47% to 210% for men2. (Yields greater than 100% occur if
people transfer into the program after the first year or take less than 5 years to
finish.) The overall yield for women is lower than for men (81% compared to 101%). The parity
index overall is 0.80, considerably below the true-parity index of 1. Twenty-four percent
of graduate students 1988-1992 were women while only 20% of the Ph.D.s 1994-1998
went to women. As found in previous studies, the attrition of women astronomy graduate students appears to
be greater than that of men. Several institutions have graduated a relatively large fraction
of women: 9 of 33 Ph.D.s (not shown in table) at the University of Texas at Austin in 1988-1992 (and 6 of 35 in
1994-1998), and 10 of 27 Ph.D.s at the University of California at Santa Cruz
1994-1998. A few others are at the other end of the distribution, such as the
University of Chicago (5 women of 37 Ph.D.s, 1994-1998) or Cornell University
(4 women of 29 Ph.D.s, 1994-1998) — perhaps surprisingly, as both had admitted
1988-1992 graduate school classes that were 1/3 female.

Women are hired as assistant professors by the top 25 astronomy departments at
roughly their presence in the Ph.D. candidate pool: they are ~20% of possible
candidates and ~20% of recently hired assistant professors, with large statistical
errors. In this respect, astronomy compares favorably to chemistry and similarly to
physics in terms of producing new women assistant professors.

It appears that the situation in top astronomy departments, while perhaps not
ideal, is at least better than in our sister fields of chemistry (where too few women
assistant professors are being hired) and physics (where a smaller percentage of
women are getting Ph.D.s). The number of women astronomers is growing, and
provided we are not complacent about it, should continue to do so.


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