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From |
Austin Nichols <austinnichols@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st:compare distribution of a variable across groups |

Date |
Tue, 3 Feb 2009 15:01:57 -0500 |

Mandy fu <mandy.fu1@gmail.com>: You can look at the whole distribution fairly easily-- help kdensity help tw kdensity gets you started, or you can modify this example: ssc install vioplot sysuse nlsw88, clear keep if race<3 tw kdensity wage, by(race) replace grade=8 if grade<9 la def grade 8 "8 or less" la val grade grade egen g=group(race grade), label vioplot wage, over(g) horiz yla(,angle(0)) name(w) g c=cond(wage>0,wage^(1/3),-abs(wage)^(1/3)) vioplot c, over(g) horiz yla(,angle(0)) name(c) You might have to take the cube root of wage if it is too skewed to see the distribution without transformation (wages are positive, but earnings and such need not be, which is why I use the convoluted syntax above). Note the large literature on how difficult it is to estimate the effect of education on wages without obtaining badly biased results; see e.g. http://www.nber.org/papers/w7769 Percentiles and such can be obtained from _pctile (and many other commands, not all of which allow survey weights) or qreg (in a regression framework). I think you mean "standard deviations" rather than "standard errors" below, but don't make the mistake of thinking wages or incomes are normally (or even symmetrically) distributed. On Mon, Feb 2, 2009 at 4:46 PM, Mandy fu <mandy.fu1@gmail.com> wrote: > Hi all, > > I'm wondering if anyone here could give me some suggestion on > comparing a variable's distribution across several groups. > > I'm going to compare the effect of education on wage rates by racial > groups. Here's what I'm thinking: > > step 1. > I will check the means,standard errors,and ranges of wages by racial groups. > step 2. > I will check percentile wage rates,like decimal percentile, for each group. > > What I'd like to ask is: what is the usual way to compare the > distribution of a variable across several groups? My concern is > that,maybe I would miss something if only comparing the means or > standard errors of wages. So, I'm curious how most researchers deal > with this . * * 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/

**Follow-Ups**:**Re: st:compare distribution of a variable across groups***From:*Mandy fu <mandy.fu1@gmail.com>

**References**:**st:compare distribution of a variable across groups***From:*Mandy fu <mandy.fu1@gmail.com>

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