D statistic for a fitted CTA tree

Computes the parsimony-normalized classification criterion:

Usage

cta_d_stat(tree)

Arguments

tree

A cta_tree from oda_cta_fit.

Value

Numeric scalar D, or NA_real_.

Details

$$D = \frac{100}{\text{ESS} / \text{strata}} - \text{strata}$$

where strata is the number of terminal leaf endpoints and ESS is tree$overall_ess (WESS when case weights are active, ESS otherwise).

Returns NA_real_ when:

• tree$no_tree is TRUE;

• tree$overall_ess is missing, non-finite, or \(\le 0\);

• strata < 2.

See also

cta_strata, cta_min_terminal_denom