Table 2.

Power to detect changes within groups (effectiveness) and minimum detectable differences between groups (relative effectiveness) with 5% significance, two-tailed.

Outcome	MDIa	Assumed values		Effectiveness	Relative effectiveness
		SDb,c	Pre-post r c	Power	MDDd
Primary outcomes
Work sitting time	45 minutes	90	0.6	90%	50 minutes
Overall sitting time	45 minutes	90	0.6	90%	50 minutes
Secondary outcomes
Work prolonged sitting time	45 minutes	120	0.6	67%	65 minutes
Overall prolonged sitting time	45 minutes	120	0.6	67%	65 minutes
Work standing time	30 minutes	70	0.6	79%	35 minutes
Overall standing time	30 minutes	70	0.6	79%	35 minutes
Work stepping time	15 minutes	20	0.7	>99%	10 minutes
Overall stepping time	15 minutes	30	0.7	96%	15 minutes

^aminimum difference of interest.

^bstandard deviation.

^cassumed values based on unpublished data from the Stand Up Victoria trial

^dminimum detectable difference with 80% power