49 3 As seen in Table 2, the ICC for patients with HNC (0.886; 95% CI=0.784-0.942) showed a good correlation between the test and retest, and a moderate correlation for healthy controls (ICC=0.525; 95% CI=0.272-0.712). The SEM was 0.76 (4.0%) in patients, and 1.45 (9.0%) in healthy controls, with an SDC of 2.12 (11.1%) and 4.02 (24.8%), respectively. The SEM values indicate that there was an expected random variation in all MAT scores of 0.76 points (4.0%) for patients with HNC and 1.45 points (9.0%) for healthy controls.21 The SDC values indicate that the difference between two tests needs to be at least 2.12 points (11.1%) for patients with HNC and 4.02 points (24.8%) for healthy controls to be considered a true change in masticatory performance which is not caused by a measurement uncertainty. The Bland-Altman plots (Figure 1 and 2) show that 95% of the data lie between the LoA, with a consistent variability, indicating no systematic variation in performance between two measurements. Table 2. Reliability of the Mixing Ability Test for patients with head and neck cancer and healthy controls Patients (n = 34) Healthy Controls (n = 42) Test mean (SD) Test median (IQR) 19.12 (4.56) 19.30 (8.68) 16.42 (2.04) 15.80 (2.60) Retest mean (SD) Retest median (IQR) 19.14 (4.80) 19.20 (9.58) 15.95 (2.30) 15.65 (3.13) Difference test-retest, mean (SD) -0.02 (2.26) 0.47 (2.10) ICC2,1 0.886 0.525 95% CI 0.784 - 0.942 0.272 - 0.712 SEM 0.76 1.45 SEM% 4.0% 9.0% SDC 2.12 4.02 SDC% 11.1% 24.8% 95% LoA -4.46 to 4.42 -3.65 to 4.59 CI: Confidence Interval, ICC: Intraclass Correlation Coefficient, IQR: Interquartile Range, LoA: Limits of Agreement, SEM: Standard Error of Measurement, SDC: Smallest Detectable Change Test and retest showed no significant differences for both patients (Z=-0.206, p=0.837) and healthy controls (Z=-1.406, p=0.160). Age and sex were significantly different between patients and healthy controls (p<0.001 and p=0.001, respectively). A significant effect of age on MAT outcome in both patients and healthy controls was observed (test: χ2(6)=19.812; p=0.003, retest: χ2(6)=16.127; p=0.013), in which a higher age leads to a higher MAT score and therefore a lower mixing ability. Sex (test: χ2(1)=0.054; p=0.815, retest: χ2(1)=0.611; p=0.434) did not show an effect.