Table 4.

Interpreting change based on the natural distribution of week 2 – week 1 difference scores.

	Worse/Lower Scores				Improved/Higher Scores
Sway Stances	10%	15%	20%	Normal Variability	20%	15%	10%
Balance – Overall	−7.48	−5.44	−4.77	−4.77, 6.73	6.73	8.46	10.97
Feet Together	−9.19	−4.02	−2.95	−2.95, 1.88	1.88	2.63	4.98
Tandem Stance Right Foot Forward	−12.33	−5.41	−3.33	−3.33, 6.9	6.90	9.44	14.78
Tandem Stance Left Foot Forward	−7.29	−6.05	−4.76	−4.76, 7.75	7.75	10.44	16.82
Single Leg Right	−22.27	−13.28	−7.59	−7.59, 19.76	19.76	24.09	29.50
Single Leg Left	−17.36	−13.98	−8.48	−8.48, 10.02	10.02	12.72	24.65

The difference scores in this table were derived by subtracting the Week 1 scores from the Week 2 scores. The 10% score refers to the difference score that occurs in 10% or fewer of the total sample, and the 20% difference score refers to the difference score that occurs in 20% or fewer of the total sample. Normal variability represents the range of difference scores obtained by 60% of the sample. For example, a difference score of 10.97 on the Sway Balance - Overall represents improved performance that is seen in 10% or fewer of the sample. A difference score of −5.44 on the Sway Balance - Overall represents a worsening in performance that is seen in 15% or fewer of the sample. For all tests, higher scores denote better performance.