Table 2. Comparison of upward and downward crossings in the three comparison datasets.
| Model Parameter | Link Function | Data Set | Downward Crossings | Upward Crossings | ||
|---|---|---|---|---|---|---|
| Estimate (95% CI) | Tukey Group2 | Estimate (95% CI) | Tukey Group2 | |||
| Mu (mean for non-zero values) | Log | Research Colony | 0.393 (0.323, 0.464) | b | 0.447 (0.352, 0.541) | ab |
| Overweight Subset | 0.0624 (-0.303, 0.428) | a | 0.972 (0.746, 1.20) | a | ||
| Underweight Subset | 0.723 (0.298, 1.15) | b | 0.155 (-0.382, 0.691) | b | ||
| Sigma (coefficient of variation for non-zero values) | Log | Research Colony | -0.435 (-0.507, 0.363) | a | -0.169 (-0.241, -0.0972) | b |
| Overweight Subset | 0.0808 (-0.143, 0.304) | a | 0.200 (-0.376, -0.0248) | a | ||
| Underweight Subset | -1.20 (-2.17, -0.240) | a | -0.828 (-1.65, -0.00601) | b | ||
| Nu (probability of a zero value) | Logit | Research Colony | -2.88 (-3.35, -2.41) | a | -2.07 (-2.40, -1.73) | b |
| Overweight Subset | 0.231 (-0.559, 1.020) | a | -2.66 (-3.65, -1.67) | a | ||
| Underweight Subset | -1.10 (-3.91, 1.71) | a | -11.2 (-206, 184) | ab | ||
1 Values of coefficients (with 95%-CI) for the zero-adjusted gamma model fitted to the number of upward and downward crossings in each of the three comparison datasets, together with p-values. The three parameters of the zero-adjusted model correspond to the probability of obtaining a zero value (Nu), the mean of the distribution for non-zero values (Mu) and the coefficient of variation for non-zero values (Sigma).
2 Tukey groups indicate whether differences exist between groups for a parameter within a model; groups with different letters are significantly different at the 5% significance level.