Accuracy Assessment

The GNN maps are evaluated in several ways, as described in Ohmann and Gregory (2002) and Ohmann et al. (2007, in press). Accuracy assessment products for each modeling region include the following:

• For GNN species model:
  • kappa statistics for individual tree species (from cross-validation).
• For GNN species-size model:
  • correlation coefficients for core vegetation variables (from cross-validation)
  • confusion matrix for vegetation class (from cross-validation)
  • kappa statistics for vegetation class (from cross-validation)
  • area distribution for vegetation class (compares the distribution of forest area among vegetation classes, as predicted from GNN and as estimated from the systematic sample of grid plots, to provide a regional view of overall accuracy).

To download GNN map products and associated accuracy assessment reports, visit the modeling regions and schedule page and then click on your region of interest.