A matched case control study carried out to investigate the connection between X-ray usage and acute myeloid leukemia in childhood. The pairs are matched by age, race and county of residence.
data(amlxray)
A data frame with 238 observations on the following 11 variables.
ID
a factor denoting the matched pairs
disease
0=control, 1=case
Sex
F
or M
downs
Presence of Downs syndrome: no
or yes
age
Age in years
Mray
Did the mother ever have an Xray: no
or yes
MupRay
Did the mother have an Xray of the upper body
during pregnancy: no
or yes
MlowRay
Did the mother have an Xray of the lower body
during pregnancy: no
or yes
Fray
Did the father ever have an Xray: no
or yes
Cray
Did the child ever have an Xray: no
or yes
CnRay
Total number of Xrays of the child 1
=none
< 2
=1 or 2 < 3
=3 or 4 < 4
= 5 or more