Exercise :
The relation between length of lactation period and breast cancer was investigated in randomly selected 270 healthy females and 135 breast cancer patients. The length lactation period was divided into 4 groups, ‘less than 3 months’, ‘3 to 6 months’, ‘6 to 9 months’, and ‘9 to 11 months’, and the results are shown below. Analyze whether the length of lactation period is related to breast cancer risk. (C Hirose: Statistical Data Analysis, 1983.)
Comparative Verification Test
Cochran-Armitage test (Chi-square value): StatMate, 6.2891; SPSS, 6.2895; EZR, 6.5161.
Cochran-Armitage test (P value): StatMate, 0.01215; SPSS, 0.01; EZR, 0.01069.
The test for departures from a linear trend: StatFinale, 0.516544.
The original data by Chihiro Hirose, who introduced this testing method in his book, had four levels of “dosage 1, 2, 3, 3.7”. EZR could not handle “dosage 3.7”, so it displayed the results as if “dosage, 1, 2, 3, 4” had been entered. SPSS does not have this program, but it can be calculated using the cross-tabulation function. compute catrend = 6.274*405/404 = 6.2895. compute sigca = 1- cdf.chisq(catrend,1) = 0.01215. See IBM Support: Can I run a Cochran-Armitage test for trend in SPSS Statistics?
Reports of EZR
※Click pics to enlarge.
