Table 2.

Minimum detectable effect sizes in our study. Each row shows a different quantity measured in our study. The third column shows the mean change in this quantity, subtracting the value measured before TV viewing from that measured after, averaged over all participants for whom the measurement was available. The fourth column shows 0.7 times the within-group standard deviation, which is the smallest difference in this change we would expect to be able to detect.

change in: (after–before)	units	mean value of change	minimum detectable difference in change
time taken to complete coordination task	seconds	−2.9	4.3
time spent buzzing on coordination task	seconds	−0.78	0.9
percentage of time spent buzzing	% points	−1.2	1.3
time taken to complete all three balance tests	seconds	−3.2	2.7
time taken to complete ramp task	seconds	−1.1	0.9
time taken to complete beam task	seconds	−1.1	1.2
time taken to complete steps task	seconds	−0.4	1.1
number of blocks displaced		−0.06	0.2
chest accelerometer: standard deviation of accelerations recorded during all three balance tests, mean over the three axes	m s−2	0.06	0.16
chest accelerometer: standard deviation of accelerations recorded during all three balance tests, mean over the three axes	m s−2	0.10	0.12