Comparison of model evaluation statistics for boosted regression tree models (BRT) for four macroinvertebrate metrics for development (develop) and validation (valid) data sets at two spatial scales (full region and four ecoregions), number of variables in final model in parentheses.

Validation models run with the same variables as the final development model.*
*R2–adjusted R-squared, CV R2-Cross validation R2; EPTR–Total taxa richness of Ephemeroptera (mayflies), Plecoptera (stoneflies) and Trichoptera (caddisflies); RichTOL-Average tolerance of all taxa; INTOL_RICH-Richness of intolerant taxa; NonInsectR-Noninsect taxa richness.