In survival analysis (using, say, Kaplan-Meier curves) how can I do such comparisons between two arms? I know log-rank test, but that test is for comparison of two entire survival curves, not just medial survival time or survival rate at certain time point (say, survival rate at 12 months). Personally I don't think this type of comparison is reasonable, and actually I cannot find such single-point comparison in any survival books or statsitical journals, -- I only see this occasionally in certain poster presentations. However, we are sometimes requested to do this by some physicians (like difference or even 95% C.I. of difference of two 12-month survival rates). Any option(s) in, say, "lifetest"? Any suggestions? Thanks!
Maybe you should use Wilcoxon-rank-sum-test ,because it is nonparameter statistical method which is robust for any distribution. And log-rank is most powerful only for the survival curves both paralleled.