Question: How to compute a one tail (one way) log rank test for survival?

0

denalitastic •

**30**wrote:I have censored survival data. I have been using a log rank test to get a p-value for overall survival. For example in R I have been using the survdiff function from the survival package and the below chisq test to find a survival pvalue. However this gives you the 2 tail test p value. I am only interested in one direction, For example do the patients with some mutation have better survival. My hypothesis is such that I am not interested in the other direction. Chisq being a goodness of fit measure captures both directions. What would be the equivalent code or reasoning to capture the one way or one tail logrank p value?

Thanks

```
input<-as.formula(paste0("Surv(survival_time,censoring_status) ~ ",gene_name))
gene.survival <-survdiff(input,data=data)
p.val <- 1 - pchisq(gene.survival$chisq, length(gene.survival$n) - 1)
```

one-way one way one-tailed one tail log-rank