TreePlan Software is a San Francisco based company providing analytic add-ins for Excel: TreePlan for decision trees, SensIt for sensitivity analysis, and SimVoi for Monte Carlo simulation. TreePlan Software has been in business since 1991 and is registered with the City and County of San Francisco.




Mike Middleton (Michael R. Middleton) is the primary software developer at TreePlan Software. His first decision analysis software project was completed in 1972 while he was a Ph.D. student at Stanford University, and he developed the first version of the TreePlan decision tree add-in for Excel in 1992.


Mike is the author of four editions of the book Data Analysis Using Microsoft Excel. During 1977-2008 Mike Middleton was a full-time Professor in the School of Management, University of San Francisco, where he taught undergraduate, M.B.A., and Executive M.B.A. courses in decision modeling and data analysis.



Stanford University, Graduate School of Business
Stanford University, Operations Research
University of Iowa, Business
Iowa State University, Electrical Engineering