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From | "Dimitriy V. Masterov" <dvmaster@gmail.com> |
To | Statalist <statalist@hsphsun2.harvard.edu> |
Subject | st: how to model the size/shape of an area |
Date | Tue, 8 Nov 2011 10:27:19 -0500 |
I would like to model the dimensions of the trade areas for a set of stores. I have geocoded sales data for each store, which I used to construct a convex hull using a GIS program. Essentially, I took the nearest 80 percent of sales for each store, and then snapped a rubber band around those points to get a trade area boundary for each store. Then I calculated the area of these regions, and modeled the radii as if the trade areas were circles, using the characteristics of the area right around the store as predictors. I used a simple glm model with a log link function for the estimation. This gives terrible predictions since many of the areas are elliptical or have spike-like bulges. Does any one have any suggestions for how to model the shape and size of these regions in a better way? DVM * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/