Log-Rank and Wilcoxon Algorithm

These tests are for comparison of two or more strata of survival data.

Suppose that we have data from stratum 0 and stratum 1. Denote the ordered observed failure times by . At time , let be a positive weight function, and and are the size of the risk set and the number of events in the jth stratum, respectively. Let , .

1. Log-Rank and Wilcoxon statistic :

• is 1.0 for log-rank test
• is for wilcoxon test

2. covariance for Log-Rank and Wilcoxon statistic :

• is 1.0 for log-rank test
• is for wilcoxon test

3. Computation of Chi-Square and prob-Chi-Square :

• Chi-Square =
• prob-Chi-Square comes from function of pchisq(Chi-Square, 1, false, false)
Topic revision: r5 - 13 Sep 2005, ColeBeck

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