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From |
Tirthankar Chakravarty <tirthankar.chakravarty@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: test difference in quintiles |

Date |
Wed, 10 Jun 2009 16:26:40 +0100 |

<> This is a variation of previous advice: http://www.stata.com/statalist/archive/2009-05/msg00311.html I believe you want to test the significance of the difference of the 5th percentile for two variables using a bootstrap. If this is the case, then the code below applies: /* Bootstrap the difference of percentiles */ clear webuse nlswork, clear keep idcode year ttl_exp reshape wide ttl_exp, i(idcode) j(year) cap prog drop pctile_bs program define pctile_bs, rclass version 10 syntax varlist(max=2 min=2) [if] [in] marksample touse tokenize `varlist' local first `1' macro shift local second `*' _pctile `first' if `touse', percentiles(5) scalar pc1 = r(r1) _pctile `second' if `touse', percentiles(5) scalar pc2 = r(r1) return scalar dpc = pc1-pc2 ereturn post, esample(`touse') end bootstrap Dpc = r(dpc), reps(2000) dots: pctile_bs ttl_exp68 ttl_exp69 /* End */ Please also see the reference about pivotal statistics in a bootstrap from the previous message. T On Wed, Jun 10, 2009 at 3:57 PM, Susanne Neckermann<sneckermann@iew.uzh.ch> wrote: > Hi! > > I want to test whether the difference in the fifth percentile of two > distributions is significant. > In principle, this test should be similar to the "median" (thats the name of > the command) test already implemented in Stata, but unfortunately I cannot > program .ado files and I could not find a user-written procedure. > Any idea how to go about this? > P.S. the number of observations in the fifth percentile is pretty low > (around 6), so one might have to use something with bootstrap or > permutations. > > Thank you so much in advance > susanne > > > > * > * 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/ > -- To every ω-consistent recursive class κ of formulae there correspond recursive class signs r, such that neither v Gen r nor Neg(v Gen r) belongs to Flg(κ) (where v is the free variable of r). * * 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: test difference in quintiles***From:*Susanne Neckermann <sneckermann@iew.uzh.ch>

**References**:**Re: st: Need to Title a Second Y-Axis...***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**RE: st: Need to Title a Second Y-Axis...***From:*"Ploutz-Snyder, Robert (JSC-SK)[USRA]" <robert.ploutz-snyder-1@nasa.gov>

**st: test difference in quintiles***From:*Susanne Neckermann <sneckermann@iew.uzh.ch>

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