Type I error control and power analysis
It is questionable to attribute any observed reduction in ventilator-free days in the TEACH treatment arm to the intervention if a significant TEACH effect on adherence is not observed. Therefore, a formal hypothesis test of a TEACH treatment effect on the ventilator-free days outcome will be carried out, with type I error of 0.05, if and only if the TEACH effect on adherence is significant at the 0.05 level. This approach limits type I error to 0.05 for assessment of both outcomes.