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

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: poverty/inequality analysis |

Date |
Mon, 21 Jul 2008 16:28:19 -0400 |

Lola-- The problem is, there may be infinitely many "change in Gini (or other measure)" transformations you can apply to get to a given target. You need to impose more structure on the dispersion-changing transformation (and I would advise that you restrict it to be mean-preserving, or possibly median-preserving). My silly transformation only has one parameter, so you can vary that to find the smallest value that gets you to the requisite poverty rate or below, but if you have a transformation with even two parameters, you will in general have many choices--and your problem as stated seems to allow N parameters with N people (i.e. everyone's income can change by some unspecified amount). Once you pick a transformation, it will have various defects that a reviewer will no doubt point out after you've spent months writing the paper... On Mon, Jul 21, 2008 at 4:10 PM, Lola Jackson <lola_jackson@ymail.com> wrote: > Dear Austin, Stas, and other Statalisters, > > Thank you very much for the helpful replies. > > Austin is correct that I am working with real income data, which is not log-normal. Actually he expressed what I want to do well when he asks 'Do > you want to apply a mean-preserving contraction (the opposite of a > mean-preserving spread) and a shift in the mean, to different degrees, > to a given distribution to achieve a specified percent below a given > threshold?' – pretty much yes. I understand that this is not really how income evolves in practices, but the objective is to illustrate what combinations of changes in distribution and growth might be required to meet a given poverty reduction goal (and to compare this with current rates). > > My thinking is that with a given Lorenz curve and given mean > income, one can calculate the % of people below a numerical poverty line (or > changes in each of these variables). So I want to work out, given a specified % > of people below the poverty line and given a specified growth rate, what would > be the change in Gini (or other measure) 'required'; or alternatively given a > specified % of people below the poverty line and given a specified change in > Gini or other distribution measure, what would be the growth rate of mean > income 'required'. > > Thanks! > > Lola > * * 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/

**References**:**Re: st: poverty/inequality analysis***From:*Lola Jackson <lola_jackson@ymail.com>

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