----- Forwarded message from Wolfgang Rolke -----
>From [EMAIL PROTECTED] Sat Jan 22 10:47:51 2000
From: Wolfgang Rolke <[EMAIL PROTECTED]>
Hi,
I am looking for information (journal article, web site ect.) on the
difference in birth rates for boys and girls. Specifically I would like
to find some real data and possible explanations for this phenomena. It
seems to me that this would make a great example for an introductory
stats course.
----- End of forwarded message from Wolfgang Rolke -----
This should be on a FAQ list somewhere. Here are some bits and pieces
selected not because they are great but because they are what I have
at hand and answer some of the basic questions (while raising many
more).
>From _Populatiion: An Introduction_ by Johannes Overbeek, Harcourt
Brace Jovanovich, 1982, pp.206-207.
"Sex, of course, is one of the most readily observable components of
population structure. People may misrepresent their age, but they are
less likely to misstate their sex. The sex composition of a
population is conventionally expressed by a summarizing device called
the sex ratio, the masculinity ratio, or the ratio of males to
females.
"In the populations of most Western countries, including the United
States, the sex ratio at birth is about 105%... For American blacks the
sex ratio at birth is about 103%.
"More male than female births is a feature of most mammals..."
Then I have a preprint of a paper "Excess Female Mortality and the
Balance of the Sexes in the Population: An Estimate of the Number of
'Missing Females'" by Ansley J. Coale at Princeton.
"The masculinity ratio at birth has a limited range when calculated
from large numbers of births with accurate registration. For
aggregate births in 1962-1980 in 24 countries in Europe, the ratio
ranged from 1.05 to 1.07."
My recollection is that these differences are too large to be due to
chance, but no one knows their cause, nor why more males than females
are born. That pattern emerges in populaation records as far back as
such records have been kept.
_
| | Robert W. Hayden
| | Department of Mathematics
/ | Plymouth State College MSC#29
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