2010 RWISO Journal - Roth Williams International Society of ...

For these analyses, the desired significance level of 0.05
was reduced by a factor of 5 (for the 5 variable CPI readings:
right A-P, right vertical, left A-P, left vertical, and transverse)
to control experimentwide alpha and to avoid the risk of
type I errors. Thus a significance level of α = 0.01 was used
for each test of the condylar axis position measurements. The
results indicated statistically significant differences between
time 1 and time 2 for the positioner group in the right A-P (Δ
= 0.57 mm, t = 3.03, p = .006); right vertical (Δ = 0.59 mm,
t = 2.79, p = .009); left vertical (Δ = 0.49 mm, t = 3.05, p =
.005); and transverse (Δ = 0.78 mm, t = 3.49, p = .002) measurements.
There was no statistically significant difference in
the magnitude of condylar distraction in the left condyle in
the A-P direction (Δ = 0.20 mm, t = 0.92, N.S.).
Mixed-design analyses of variance compared the positioner
and control groups’ change in MI-CR discrepancy
over time (Table 4).
Table 4 Mixed Design Analysis of Variance for MI-CR Discrepancies from time 1 to time 2 between Control Versus Positioner Group.
Using the adjusted significance level described above
(α = 0.01), these comparisons between the 2 groups showed
no statistically significant differences in any of the 5 CPI
measurements. However, 4 of the 5 dimensions fell below
Effect F* p
Right AP Time 0.012 .915
Time x group 6.096 .019
Right vertical Time 0.266 .609
Time x group 5.203 .029
Left AP Time 2.431 .129
Time x group 6.053 .019
Left vertical Time 0.599 .445.
Time x group 4.917 034
Transverse Time 4.102 .051
* df for all tests are 1, 32.
Time x group 2.978 .094
the traditional α = 0.05 level. Graphical representations of
the change in MI-CR discrepancy over time for the positioner
and control groups are shown in Figures 6 through 10.
Figure 6 Right horizontal MI/CR discrepancy. Figure 7 Right vertical MI/CR discrepancy.
RWISO Journal | September 2010
79