downs.bc                package:boot                R Documentation

Incidence of Down's Syndrome in British Columbia

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*, 717-724.

References:

     Davison, A.C. and Hinkley, D.V. (1997)  _Bootstrap Methods and
     Their Application_. Cambridge University Press.

