TABLE 4.
NHANES VIM Results for CART, CTree, and Random Forest
| CART | CTree | Random Forest | |||
|---|---|---|---|---|---|
| Splitting Variable (Yes/No) | Splitting Variable (Yes/No) | Impurity-based VIM | Permutation-based VIM | Permutation-based VIM, P value | |
| Age (20–39, 40–59, 60+ years) | Yes | Yes | 477,183.3 | 111.4 | 0.010 |
| Gender (male, female) | Yes | Yes | 38,325.7 | 10.5 | 0.010 |
| Race/ethnicity (Hispanic, non-Hispanic White, Black, Asian, other) | No | Yes | 52,847.6 | 13.6 | 0.020 |
| Education (high-school education or less, at least some college education) | No | Yes | 25,974.0 | 4.4 | 0.010 |
| Marital status (married, not married) | No | Yes | 16,299.8 | 2.2 | 0.010 |
| Health insurance (insured, not insured) | No | Yes | 14,982.7 | 3.5 | 0.010 |
| Immigrant (born in the United States, immigrant) | No | Yes | 12,195.0 | 6.0 | 0.792 |
| Income (above federal poverty line, below) | No | No | 12,368.3 | 1.5 | 0.188 |
CART indicates results for classification and regression trees; CTree, conditional inference trees; VIM, variable importance measure.