Table 2:

Distribution-based important difference estimates of gait speed

Methods	Important difference calculation	20-m gait speed (m/min)	400-m gait speed (m/min)
		(n=2527)	(n=2425)
SEM *	${\text{SD}}_{\text{baseline}}\sqrt{1-\text{ICC}}$	4.1	2.9
Change SD	0.5×SDΔ	4.3 **	3.9 ***
Baseline SD	0.5× SDbaseline	6.4	6.5

^*Test-retest reliability (intraclass correlation coefficient, ICC) is 0.90 for 20-meter gait speed and 0.95 for 400-meter gait speed.

^**n=2220

^***n=1939

SEM: Standard Error of Measurement

SD_baseline = standard deviation of baseline gait speed

SD_Δ = standard deviation of change in gait speed from baseline to 2 year follow-up evaluation