Table 2.
Stepwise selection of predictors of response inhibition scores for the full sample (controls, PD, and PSP groups)a
| Model selection step |
|||||||||
|---|---|---|---|---|---|---|---|---|---|
| Predictors | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | BFinclusion |
| LVLC | −0.23* | −0.23* | −0.23* | −0.23* | −0.24** | −0.24** | −0.24** | −0.24** | 7.45 |
| Group | −0.76***; −0.41** | −0.75***; −0.40** | −0.73***; −0.39** | −0.75***; −0.39** | −0.77***; −0.40** | −0.73***; −0.38** | −0.69***; −0.35** | −0.68***; −0.35** | 7.84 × 106 |
| Gender | 0.16 | 0.18 | 0.17 | 0.15 | 0.14 | 0.12 | 0.07 | — | 0.44 |
| Midbrain | 0.41 | 0.42 | 0.38 | 0.41 | 0.42 | 0.11 | — | — | 0.53 |
| Brainstem | −0.27 | −0.28 | −0.24 | −0.27 | −0.30 | — | — | — | 0.46 |
| Education | −0.08 | −0.08 | −0.07 | −0.07 | — | — | — | — | 0.49 |
| Whole brain | 0.06 | 0.07 | 0.06 | — | — | — | — | — | 0.43 |
| Age | −0.06 | −0.05 | — | — | — | — | — | — | 0.41 |
| LVLC × Group | 0.03; −0.07 | — | — | — | — | — | — | — | 0.23 |
| Information criteria | |||||||||
| AIC | 136.68 | 132.95 | 131.39 | 129.85 | 128.50 | 127.68 | 126.98 | 125.78 | |
| Δ AIC | 10.90 | 7.17 | 5.62 | 4.07 | 2.72 | 1.90 | 1.20 | 0 | |
| BIC | 164.33 | 156.35 | 152.67 | 148.99 | 145.51 | 142.57 | 139.74 | 136.42 | |
| Δ BIC | 27.92 | 19.94 | 16.25 | 12.58 | 9.10 | 6.15 | 3.32 | 0 | |
aValues for predictors under the “Model selection step” columns are standardized regression coefficients (β). BFinclusion, Inclusion Bayes factor, that is, the change from before posterior inclusion odds, which indicates how much more likely the data are under models that include the predictor compared with models that exclude the predictor; LVLC, participant scores on latent variable of LC CNR; Group, controls versus PD patients versus PSP patients; Midbrain, total midbrain volume (mm3); Brainstem, total brainstem volume (mm3); Whole brain, estimated total intracranial volume (mm3); AIC, Akaike Information Criterion; BIC, Bayesian Information Criterion; Δ AIC/BIC, difference in AIC/BIC with respect to the lowest AIC/BIC value. The predictors Group and LVLC × Group are each represented by two regression coefficients: The first coefficient represents the difference between the control group and the intercept; the second coefficient represents the difference between the PD group and the intercept; and the PSP group is modeled as the intercept plus the negative of the sum of the two coefficients.
***p < 0.001;
**p < 0.01;
*p < 0.05.