Statistical Analysis
We estimated that the sample size needed to detect at least a
2000-step difference in means was 14 participants per group,
or 42 participants total, assuming a within-participant SD of
1800 steps/day, 2-sided alpha of 0.05, and beta of 0.8.
Allowing for 12% attrition, target enrollment was 48 participants. Our trial aimed to detect an increase of 2000 steps/
day, given that this was previously associated with a10%
relative reduction in the long-term incidence of CVD,