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Bivariate kernel density graphs over a grid

tddens[,bwidth(proportion)sgraphbgraphsgopt(string)bgopt(string)gridpoints(integer)format(format)msize(markersizestyle)msymbol(symbolstyle)genstub(stubname)]

tddensestimates bivariate density using a symmetric triangle kernel with bandwidth given as a proportion of sample range (optionbwidth, with default 0.2) and produces several graphs. A "heat map" is produced by default; optionsgraphshows a surface plot as points, and optionbgraphshows a bar graph that offers an alternative view of the surface. The optionssgoptandbgoptallow passing strings of options to the surface plot and bar graph, respectively. The optionsmsizeandmsymbolapply to the surface plot only. Optiongridpointsspecifies how finely the grid of density estimates should be drawn; the default is 40 intervals in each dimension or 40+1 squared (1681) density estimates. Optionformatspecifies formats for axis labels. Optiongenstubspecifies a stub name for variable names to be saved on the current dataset, containing kernel density estimates and auxiliary variables used in the graphs.

Examplesysuse auto, clear tddens price mpg, s b tddens price mpg, ge(dens)

Author oftddensAustin Nichols <austinnichols@gmail.com>

Also seeOn-line: help for spkde (if installed; findit spkde to download).