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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: make a program byable |

Date |
Mon, 24 Jun 2002 10:09:35 +0100 |

Katsuhide Isa > > Recently I wrote the following simple program > titled 'coefvar.ado' for the purpose of calculating > coefficients of variation. > > ----------coefvar.ado---------- > program define coefvar, rclass byable(recall) > version 7 > qui summ `1', det > local coefvar = r(mean)/r(sd) > di in green _col(8) `coefvar' > end > ----------coefvar.ado---------- > > But somehow it doesn't work as expected. > More specifically, when typing like > > 'bys year : coefvar basepay' > > using a data set containing multiple panels, following > results:are shown on the screen: > > __________________________________________________________________ > __________ > ___ > -> year = 1989 > 3.7137332 > > __________________________________________________________________ > __________ > ___ > -> year = 1990 > 3.7137332 > > __________________________________________________________________ > __________ > ___ > -> year = 1991 > 3.7137332 > > __________________________________________________________________ > __________ > ___ > -> year = 1992 > 3.7137332 > > __________________________________________________________________ > __________ > ___ > -> year = 1993 > .... > > and so on. Namely, they are all the same for > each year when they should vary from year > to year. > I guess something is wrong or missing with this > program, but I'm sorry I can't fix it. Gary Longton replied to the question directly. Two ther comments are that sd / mean is the definition of coefficient of variation in the literature I have encountered and that egen mean = mean(basepay), by(year) egen sd = sd(basepay), by(year) gen cv = sd / mean tabdisp year, c(cv) gets you there interactively. Nick n.j.cox@durham.ac.uk * * 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/

**References**:**st: make a program byable***From:*"Katsuhide Isa" <CQB01114@nifty.ne.jp>

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