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Characteristics of control and intervention groups with a lag in the treatment effect and with
non-compliance in two directions.
The following example[1] demonstrates the flexibility of spower and related functions from Hmisc. We simulate a 2-arm (350 subjects/arm) 5-year follow-up study for wich the control group's survival distribution is Weibull with 1-year survival of .95 and 3-year survival of .7. All subjects are followed at least one year, and patients enter the study with linearly increasing probability starting with zero. Assume (1) there is no chance of dropin for the first 6 months, then the probability increases linearly up to .15 at 5 years; (2) there is a linearly increasing chance of dropout up to .3 at 5 years; and (3) the treatment has no effect for the first 9 months, then it has a constant effect (hazard ratio of .75).
[1] Alzola CF, Harrell FE:
An Introduction to S and the Hmisc and Design Libraries. Freely available electronic book.