Power and sample-size analysis for the Royston–Parmar combined test in clinical trials with a time-to-event outcome: Correction and program update

The changes made to Royston (2018) and to power ct are i) in section 2.4 (Sample-size calculation for the combined test), to replace ordinary leastsquares (OLS) regression using regress with grouped probit regression using glm; ii) in section 4 (Examples), to revisit the worked examples of sample-size estimation in light of the revised estimation procedure; and iii) to update the help file entry for the option n(numlist). The updated software is version 1.2.0.