Table STE0. Non-inferiority test for two exponential survival curves

Power or sample size are computed based on the approximate formula for the required number of events given in the nQuery Advisor® manual appendix., see Collett, D. Modelling Survival Data in Medical Research Chapman & Hall (1994) Section 9.2 and Rothman, M., Li, N., Chen, G., Chi, G.Y.H., Temple, R., Tsou, H.H. “Design and analysis of non-inferiority mortality trials in oncology” Statistics in Medicine 22(2003) pp. 239-264. The formulas for “n per group” which are given in the nQuery Advisor® manual appendix were adapted from equations in Lakatos, E. and Lan, K.K.G. 1992. A comparison of sample size methods for the logrank statistic. Statistics in Medicine, 11: 179-91. Figure STE0 shows computations for one example for two different specifications of power. Additional values for E, and power, and “n per group if h=limit” checked against STT0, and for “n per group” tested against spreadsheet calculations.

Figure STE0. In the first two columns, nQuery Advisor® 7.0 computed n, in the second two columns, power.