Table 3.

Mixed model ANOVA (with a subject-specific random intercept) for the shape parameters, (α₁,α₂) and the rate parameters, (β₁,β₂), for a mixture of two gamma distributions fitted to the backscattered echo intensity of the rectus femoris muscle. The two factors considered are abnormalities due to CP compared to healthy volunteers, and muscle contraction (MVIC) compared to relaxed muscle. Significant differences are seen in all parameters for CP compared to healthy volunteers at the 5% level after Bonferroni correction for multiple comparisons. Significant differences are seen in the rate parameters for muscle contraction at the 5% level after Bonferroni correction for multiple comparisons. No significant interaction is observed. Log-transformations were applied to the rate parameters to approximate normality. Residual analysis shows that the mixed effects model fits the data well.

Source of variation	α1	β1	α2	β2
CP	0.0016*	0.0038*	<1E-4*	0.0001*
MVIC	0.0775	0.0002*	0.2294	<1E-4*
Interaction CP*MVIC	0.6696	0.2326	0.6925	0.5932