{smcl} {* 16mar2011}{...} {hline} help for {hi:tddens} {hline} {title:Bivariate kernel density graphs over a grid} {p 8 14}{cmd:tddens}{bind: [, {cmdab:bw:idth(}{it:proportion}{cmd:)}} {cmdab:s:graph} {cmdab:b:graph} {bind:{cmdab:sgo:pt(}{it:string}{cmd:)}} {bind:{cmdab:bgo:pt(}{it:string}{cmd:)}} {bind:{cmdab:g:ridpoints(}{it:integer}{cmd:)}} {cmdab:f:ormat(}{help format}{cmd:)} {cmdab:msiz:e(}{help markersizestyle}{cmd:)} {cmdab:ms:ymbol(}{help symbolstyle}{cmd:)} {cmdab:ge:nstub(}{it:stubname}{cmd:)} ] {p}{cmd:tddens} estimates bivariate density using a symmetric triangle kernel with bandwidth given as a proportion of sample range (option {cmd:bwidth}, with default 0.2) and produces several graphs. A "heat map" is produced by default; option {cmd:sgraph} shows a surface plot as points, and option {cmd:bgraph} shows a bar graph that offers an alternative view of the surface. The options {cmd:sgopt} and {cmd:bgopt} allow passing strings of options to the surface plot and bar graph, respectively. The options {cmd:msize} and {cmd:msymbol} apply to the surface plot only. Option {cmd:gridpoints} specifies 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. Option {cmd:format} specifies formats for axis labels. Option {cmd:genstub} specifies a stub name for variable names to be saved on the current dataset, containing kernel density estimates and auxiliary variables used in the graphs. {title:Example} sysuse auto, clear tddens price mpg, s b tddens price mpg, ge(dens) {title:Author of {cmd:tddens}} Austin Nichols {title:Also see} {p 0 19}On-line: help for {help spkde} (if installed; {stata "findit spkde":findit spkde} to download).{p_end}