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help for kdens2
---------------------------------------------------------------------------------------- Bivariate kernel density estimation kdens2 varnameY varnameX [if exp] [in range] [, n(#) xwidth(#) ywidth(#)
saving(name) replace nodraw color {cmd:*) ]
Description kdens2 produces bivariate kernel density estimates using a Gaussian kernel. For
version 12.1 of Stata, a graph is produced with twoway contourline, or optionally
twoway contour. For versions 10 and 11 of Stata, {kdens2} graphs the result using
Adrian Mander's surface plot routine. If Y- and X-variable labels are available,
they are used to label the graph.