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| downs.bc   | R Documentation   |
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Incidence of Down's Syndrome in British Columbia
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Description
~~~~~~~~~~~

The ``downs.bc`` data frame has 30 rows and 3 columns.

Down's syndrome is a genetic disorder caused by an extra chromosome 21
or a part of chromosome 21 being translocated to another chromosome. The
incidence of Down's syndrome is highly dependent on the mother's age and
rises sharply after age 30. In the 1960's a large scale study of the
effect of maternal age on the incidence of Down's syndrome was conducted
at the British Columbia Health Surveillance Registry. These are the data
which was collected in that study.

Mothers were classified by age. Most groups correspond to the age in
years but the first group comprises all mothers with ages in the range
15-17 and the last is those with ages 46-49. No data for mothers over 50
or below 15 were collected.

Usage
~~~~~

::

    downs.bc

Format
~~~~~~

This data frame contains the following columns:

``age``
    The average age of all mothers in the age category.

``m``
    The total number of live births to mothers in the age category.

``r``
    The number of cases of Down's syndrome.

Source
~~~~~~

The data were obtained from

Geyer, C.J. (1991) Constrained maximum likelihood exemplified by
isotonic convex logistic regression. *Journal of the American
Statistical Association*, **86**, 717â€“724.

References
~~~~~~~~~~

Davison, A.C. and Hinkley, D.V. (1997) *Bootstrap Methods and Their
Application*. Cambridge University Press.
