biodex 950-440 - Page 156

156 Biodex Medical Systems, Inc. © 2017
Exploratory analysis of the five commonly used reference databases with CTSIB testing on the
Biodex Balance Systems yielded varying degrees of positive skewness (range: 0.5 to 6.3),
particularly for the less challenging CTSIB conditions (Figure D.3). Additionally, the exploratory
analyses revealed the lower boundaries of two standard deviations from the mean to cross zero
for two of the conditions (Table D.1).
Table D.1. Results of the exploratory analysis conducted on the five most commonly used reference databases for CTSIB testing
on the Biodex Balance Systems.
Thus, to improve using the multiples of the standard deviation to interpret scores, further
analyses were conducted to identify the optimal data transformation. Specifically, Box-Cox
Transformational Analyses were conducted to determine the optimal data transformation. This
procedure examines a variety of transformations, followed by plotting of the skewness value
against each transformation. By examining the plots (Figure 4), the optimal transformation that
best reduced the skewness (closest to zero) across the four CTSIB conditions could be
identified.
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Figure D.3. Positive skewness was more evident in the less challenging (left) than the more challenging
(right) CTSIB conditions.