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From |
jpitblado@stata.com (Jeff Pitblado, StataCorp LP) |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Kdensity functions on the axes of a scatterplot |

Date |
Fri, 02 Apr 2004 18:56:28 -0600 |

"Daniel Egan" <heteroskedastic@hotmail.com> ask about resting kernel density estimates of two variables on the respective axis in a twoway scatter plot: > I am interested in creating a scatterplot graph which would include kdensity > functions aligned along the respective variable axes. This could also be > (less functionally done) using scatter points along the axes to indicate > frequency, but this is not optimal. > > The command lines below are as close as I have come to what I want, but I > would guess that there is some form of tick rule that could be used to > create these, or at least I hope. > sysuse auto > > gen xnought = 130 > > gen ynought = 30 > > twoway (scatter turn length, msymbol(circle) msize(medium)) (scatter ynought > length, sort msymbol(circle) msize(vsmall)) (scatter turn xnought, > msymbol(circle) msize(vsmall)) > > What I would very much like to end up with is a kdensity function on both > axes, similar to the one created for the x-axis using: > twoway (scatter turn length, msize(vsmall)) (kdensity length, yaxis(2) epan > clpat(shortdash) clwidth(vthin)) (scatter turn xnought), yscale(range(0.0 > 2) axis(2)) > > Since the above command line uses up the right axes, I would prefer not to > use it if possible. I am using StateSE 8. Some preliminary work needs to be done to get the KDE's to hug the respective axis. Here is an example using Daniel's example. Note the -horizontal- option used in the second -kdensity- plot. ***** BEGIN: ex.do sysuse auto, clear // add observations to get smoother KDE's set obs 200 // figure out an upper bound to get KDE's to hug the axis kdensity length, gen(x h) nograph sum h local max_len = (r(max)-r(min))*10 drop x h kdensity turn, gen(x h) nograph sum h local max_turn = (r(max)-r(min))*10 twoway (scatter turn length, /// msize(vsmall) /// xtitle("") /// yvarlab("`:var lab turn' VS. `:var lab len'") /// ytitle("`:var lab turn'") /// xtitle("`:var lab length'") /// ) /// (kdensity length, /// clpat(shortdash) /// yvarlab("kernel density: `:var lab length'") /// xaxis(2) /// yaxis(2) /// xscale(axis(2) off) /// yscale(axis(2) range(0 `max_len') off) /// ) /// (kdensity turn, /// horizontal /// clpat(shortdash) /// yvarlab("kernel density: `:var lab turn'") /// xaxis(3) /// yaxis(3) /// xscale(axis(3) range(0 `max_turn') off) /// yscale(axis(3) off) /// ) /// ||, /// // blank ***** END: ex.do --Jeff jpitblado@stata.com * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**st: Measuring the reliability of a questionnaire***From:*Cristian Pattaro <cristian@biometria.univr.it>

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