Report 55: Summarizing Multiple
Aspects of Model Performance in a Single Diagram
Taylor, Karl E.
April 2000, 33 pp.
A diagram has been devised that can provide a concise statistical summary
of how well patterns match each other in terms of their correlation, their
root-mean-square difference and the ratio of their variances. Although
the form of this diagram is general, it is especially useful in evaluating
complex models, such as those used to study geophysical phenomena. Examples
are given showing that the diagram can be used to summarize the relative
merits of a collection of different models or to track changes in performance
of a model as it is modified. Methods are suggested for indicating on these
diagrams the statistical significance of apparent differences, and the
degree to which observational uncertainty and unforced internal variability
limit the expected agreement between model-simulated and observed behaviors.
The geometric relationship between the statistics plotted on the diagram
also provides some guidance for devising skill scores that appropriately
weight among the various measures of pattern correspondence.(pdf