Introductory Biostatistics

TABLE E11.12

Cases

Controls Exposed Unexposed

Exposed 25 22

Unexposed 9 21

(a) Find a 95% confidence interval for the odds ratio measuring the

strength of the relationship between the disease and the exposure.

(b)Test for the independence between the disease and the exposure.

11.13 A study in Maryland identified 4032 white persons, enumerated in a
nono‰cial 1963 census, who became widowed between 1963 and 1974
(Helsing and Szklo, 1981). These people were matched, one to one, to
married persons on the basis of race, gender, year of birth, and geog-
raphy of residence. The matched pairs were followed in a second census
in 1975.
(a) We have the overall male mortality shown in Table E11.13a. Test
to compare the mortality of widowed men versus married men.

TABLE E11.13a

Married Men

Widowed Men Dead Alive

Dead 2 292

Alive 210 700

(b)The data for 2828 matched pairs of women are shown in Table

E11.13b. Test to compare the mortality of widowed women versus

married women.

TABLE E11.13b

Married Women

Widowed

Women Dead Alive

Dead 1 264

Alive 249 2314

11.14 Table E11.14 at the end of this chapter provides some data from a
matched case–control study to investigate the association between the
use of x-ray and risk of childhood acute myeloidleukemia. In each
matched set or pair, the case and control(s) were matched by age, race,
and county of residence. The variables are:

EXERCISES 435