Software and Data After completing the model or models, it is important to validate the results. If there are known examples of what is being modeled (i.e., known deposits, animal sightings), these can be used to test how well the model classifies known examples. The Area Frequency tool in the Spatial Data Modeller toolbox provides a measurement of the efficiency of prediction measure. Lacking known examples, the judgment of the experts and field testing are required to validate the model. For more information, contact Gary Raines at garyraines.earthlink.net. Further Reading An, P., W. M. Moon, and A. N. Rencz, 1991. “Application of fuzzy set theory for integration of geological, geophysical and remote sensing data.” Canadian Journal of Exploration Geophysics, V. 27, No. 1, pp. 1–11. Bonham-Carter, G. F., 1994. Geographic Information Systems for Geoscientists—Modelling with GIS. New York: Elsevier Science, pp. 291–302. Eddy, B. G., G. F. Bonham-Carter, and C. W. Jefferson, 2010. “Mineral potential analyzed and mapped at multiple scales—a modified fuzzy logic method using digital geology,” Harris, J. R. (editor), in GIS Applications in Earth Sciences: Special Publication. Geological Association of Canada, Special Publication 44, pp. 143–162. Nykanen, V., D. I. Groves, V. J. Ojala, P. Eilu, and S. J. Gardoll, 2008. “Reconnaissance-scale conceptual fuzzy-logic prospectivity modeling of iron oxide copper-gold deposits in the northern Fennoscandian Shield,” Australian Journal of Earth Science. V. 55, pp. 25–38. Raines, G. L., and G. F. Bonham-Carter. 2006. “Exploratory Spatial Modelling Demonstration for Carlin-type deposits, Central Nevada, USA, using Arc-SDM,” Harris, J. R. (editor), in GIS Applications in Earth Sciences: Special Publication. Geological Association of Canada, Special Publication 44, pp. 23–52. About the Authors Gary L. Raines retired as a research geologist for the U.S. Geological Survey in Reno, Nevada. His research focused on the integration of geoscience information for predictive modeling in mineral resource and environmental applications. He now teaches classes in spatial modeling. Don L. Sawatzky retired as a research geologist for the U.S. Geological Survey in Reno, Nevada. His research focused on computerized analyses in remote sensing, geophysics, and structural geology. Graeme F. Bonham-Carter retired as a research geologist for the Geological Survey of Canada, Ottawa. He is interested in applications of GIS to mineral exploration and environmental problems. For 10 years, he was editor-in-chief of Computers & Geosciences, a journal devoted to all aspects of computing in the geosciences. Boolean and fuzzy logic models. The model uses Bitwise OR and AND in place of Fuzzy OR and AND. The fuzzy gamma is replaced by a Bitwise OR, which is most similar to a fuzzy gamma. www.esri.com ArcUser Spring 2010 13