January 14, 2009: RTP, NC – Researchers S. Stanley Young, Ph.D., Assistant Director of the National Institute
of Statistical Sciences, Heejung Bang, Ph.D., of Cornell University and Kutluk Oktay. MD, FACOG, Professor
of Obstetrics & Gynecology and Director, Division of Reproductive Medicine & Infertility Department of
Obstetrics & Gynecology from New York Medical College, wrote a paper, “Cereal-Induced Gender Selection?
Most Likely a Multiple Testing False Positive,” which has been published in the January 14, 2009 online issue
of the Proceedings of the Royal Society B. The paper questions the claims made by Mathews, Johnson and Neil
(2008) in their article “You are What your Mother Eats” that was published in the April 22, 2008 Proceedings
of the Royal Society B, and generated over 50,000 Google hits due to media interest.
Young, Bang & Oktay note that the original research by Mathews, Johnson & Neil implied that children
of women who eat breakfast cereal are more likely to be boys than girls. Young, Bang & Oktay assert that the
result of the original study is easily explained as chance. Young, Bang & Oktay examined the data sets from the
original study and noted that 132 food items were tested for two time periods, totaling 264 statistical tests. With
this many tests, it is quite likely that some apparent statistical significance will occur simply by chance.
At the standard significance level of 5% (that is, there is 5% chance that the data will show an effect
even when there is none), the 264 tests will yield approximately 13 false positives unless the analysis is adjusted
to account for multiple testing. Young, Bang & Oktay argue that this is precisely what happened.
“This paper comes across as well-intended, but it is hard to believe that women can increase the
likelihood of having a baby boy instead of a baby girl by eating more bananas, cereal or salt. Nominal statistical
significance, unadjusted for multiple testing, is often used to lend plausibility to a research finding; with an
arguably implausible result, it is essential that multiple testing be taken into account with transparent methods
for claims to have any level of credibility,” note Young, Bang & Oktay.
About NISS
The National Institute of Statistical Sciences was established in 1990 by the national statistics societies
and the Research Triangle universities and organizations, with the mission to identify, catalyze and foster high-impact, cross-disciplinary and cross-sector research involving the statistical sciences. NISS is dedicated to strengthening and serving the national statistics community, most notably by catalyzing community members’ participation in applied research driven by challenges facing government and industry. NISS also provides career development opportunities for statisticians and scientists, especially those in the formative stages of their careers. NISS is located in Research Triangle Park, North Carolina.
For more information about the NISS, go to www.niss.org.
About The Royal Society
The Royal Society is an independent academy promoting the natural and applied sciences. Founded in
1660, the Society has three roles, as the UK academy of science, as a learned Society, and as a funding agency.
It responds to individual demand with selection by merit, not by field. As we prepare for our 350th anniversary
in 2010, we are working to achieve five strategic priorities, to:
• Invest in future scientific leaders and in innovation
• Influence policymaking with the best scientific advice
• Invigorate science and mathematics education
• Increase access to the best science internationally
• Inspire an interest in the joy, wonder and excitement of scientific discovery
About Proceedings of Royal Society B
Proceedings of the Royal Society B is the Royal Society’s flagship international biological research
journal, dedicated to the rapid publication and broad dissemination of high-quality research papers, reviews
and comments and reply papers. Its scope is diverse and incorporates all areas of the biological sciences. It
is particularly noted for ecology in the widest sense and behavioral and evolutionary biology. All papers are
stringently peer-reviewed and the criteria for publication include scientific excellence, originality and interest
across biological disciplines. To read the current issue of the journal, go to: http://publishing.royalsociety.org/
index.cfm?page=1569.
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