The role of menstrual and reproductive factors in the epidemiology of breast cancer has been reassessed using pooled data from three large case-control studies of breast cancer from several Italian regions (Negri et al., 1988). In Table E1.24 data are summarized for age at menopause and age at first live birth.
Age at first live birth Cases Controls
|
22
|
621
|
898
|
|
22-24
|
795
|
909
|
|
25-27
|
791
|
769
|
|
b28
|
1043
|
775
|
|
Age at menopause
|
|
|
|
45
|
459
|
543
|
|
45-49
|
749
|
803
|
|
b50
|
1378
|
1167
|
(a) For each of the two factors (age at first live birth and age at meno- pause), choose the lowest level as the baseline and calculate the odds ratio associated with each other level.
(b) For each of the two factors (age at first live birth and age at meno- pause), calculate the generalized odds and give your interpretation. How does this result compare with those in part (a)?