Table STT0. Log rank test of survival in two groups: all followed for fixed time, constant hazard ratio.

Computed using the equation shown in nQuery Advisor® manual Appendix. Figure STT0 shows computations for one example. Solutions for significance level .01 and .2 two-sided, group one proportion .05, .55, .95, group two proportion .1, .5, .9 and power 50 and 99 to sample size and sample sizes back to power checked for exact agreement against Table 9.2 in Machin D, Campbell MJ (1987) Statistical Tables for the Design of Clinical Trials, Blackwell Scientific Publications Oxford.

Figure STT0. In the first column, nQuery Advisor® 7.0 has solved for sample size, in the second column for power.