System Utilities - biodex BALANCE SYSTEM SD Operation & Service Manual

12. SYSTEM UTILITIES

Medial/Lateral (M/L) Stability Index: Represents the variance of foot platform displacement in
degrees, from level, for motion in the frontal plane.
Medical/Lateral Stability Index =
Mean Deflection: Average position for the patient in all motions throughout the test.
A/P Mean Deflection: Average position of side-to-side motion for the patient throughout the test.
A/P Mean Deflection =
M/L Mean Deflection: Average position for the patient in the frontal plane throughout the test.
M/L Mean Deflection =
Standard Deviation: The amount of variability in the statistical measure. A low standard deviation
demonstrates that the range of values from which the mean was calculated were close together.
Standard Deviation =
NOte: Mean, A/P and M/L Deflections are from the patient's actual position in contrast to the Stability
Index, which is a variance from level as established during the centering patient portion of the test proto-
col. The resulting scores for Mean, A/P and M/L Deflections are not statistically effected by the centering
process.
REPORTS
Dl =
x
∑
Mean Deflection =
2
X + Y
n
(X , Y ) =
n n
=
∑
n
∑
X
n
n
n
∑
(X
n
— 9-2 —
2
∑ (0 - X)
number of samples
∑ (X
, Y )
n n
n
n
2
(position vector magnitude)
n
(
(
=
n = # of samples
Y
n
Y
n th sample
n =
n
n = # of samples
X
n th sample
n =
n = # of samples
2
- X)
n
X
n th sample
n =
n
X = mean deflection
n