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st: Sensitivity of non-parametric tests to N
I have a variable T (which is time to failure) for a binary failure event. I
wish to test whether five groups, assumed to be homogenous, have the same
survivor function. So, I have tried using:
sts test group, logrank <assuming proportional hazards>
sts test group, wilcoxon <assuming hazards vary in ways other than
proportionally and censoring patterns are similar across groups>
sts test group, peto <<assuming hazards vary in ways other than
proportionally and censoring patterns are different across groups>
All of these tests results indicate lack of equality (i.e. p-values <
0.05). I was wondering could that in part due to the sizeable groups I have
(about 120-200 patients per group), or is that real evidence of inequality
in survivor functions.
Many thanks for your help in advance.
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