Introductory Biostatistics

(Chris Devlin) #1

12150


122203


21170


21242


221217


222220


31114


3123


32196


32250;


PROC FREQ;


WEIGHT COUNT;


TABLES SMOKESHIPCANCER/CMH;


The result is given in a chi-square form (X^2 ¼ 7 :601,p¼ 0 :006); CMH stands
for the Cochran–Mantel–Haenszel statistic; noting thatð 2 : 76 Þ^2 ¼ 7 :601.


Example 6.9 A case–control study was conducted to investigate the relation-
ship between myocardial infarction (MI) and oral contraceptive use (OC). The
data, stratified by cigarette smoking, are given in Table 6.11. An application of
the Mantel–Haenszel procedure yields the results shown in Table 6.12. The
combinedzscore is


TABLE 6.12
Smoking
No Yes
a 425
r 1 c 1
n
2.52 18.70
r 1 r 2 c 1 c 2
n^2 ðn 1 Þ
2.25 14.00
ad
n

3.57 18.84
bc
n
2.09 12.54

TABLE 6.11


Smoking OC Use Cases Controls


No Yes 4 52
No 34 754
Yes Yes 25 83
No 171 853


222 COMPARISON OF POPULATION PROPORTIONS

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