如题

查了很多基尼公式，好像和这里面的都不同，请教这里的基尼系数的公式还原出来是什么样的？拜谢！！！


program ineqdeco, sortpreserve rclass

version 8.2
syntax varname(numeric) [aweight fweight] [if] [in] ///
        [, BYgroup(varname numeric) Welfare Summarize ]

if "`summarize'" != "" local summ "summ"
if "`welfare'" != ""    local w "w"
local inc "`varlist'"

tempvar fi totaly py gini wgini im1 i0 i1 i2                         ///
  nk vk fik meanyk varyk lambdak loglamk lgmeank                     ///
  thetak im1k i0k i1k i2k  ginik pyk                                 ///
  im1b i0b i1b i2b  wginik                                      ///
  ahalf a1 a2 ahalfk a1k a2k                                               ///
  whalf w1 w2 whalfk w1k w2k                                         ///
  ahalfb a1b a2b edehalfk ede1k ede2k                                  ///
  edehalf ede1 ede2 withm1 with0 withh with1 with2                      ///
  awithh awith1 awith2 wi first  
  

if "`weight'" == "" gen byte `wi' = 1
else gen `wi' `exp'

marksample touse
if "`bygroup'" != "" markout `touse' `bygroup'

qui count if `touse'
if r(N) == 0 error 2000

lab var `touse' "All obs"
lab def `touse' 1 " "
lab val `touse' `touse'

if "`bygroup'" != "" {
        capture levelsof `bygroup' if `touse' , local(gp)
        qui if _rc levels `bygroup' if `touse' , local(gp)
        foreach x of local gp {
                if int(`x') != `x' | (`x' < 0) {
                        di as error "`bygroup' contains non-integer or negative values"
                        exit 459
                }
        }
}

set more off
       
quietly {

        count if `inc' < 0 & `touse'
        noi if r(N) > 0 {
                di " "
                di as txt "Warning: `inc' has `r(N)' values < 0." _c
                di as txt " Not used in calculations"
        }
       
        count if `inc' == 0 & `touse'
        noi if r(N) > 0 {
                di " "
                di as txt "Warning: `inc' has `r(N)' values = 0." _c
                di as txt " Not used in calculations"
        }
       
        replace `touse' = 0 if `inc' <= 0  // this replaces former 'badinc' stuff

        noi if "`summ'" != "" {
                di " "
                di as txt "Summary statistics for distribution of " _c
                di as txt "`inc'" ": all valid cases"
                sum `inc' [w = `wi'] if `touse', de
        }
        else  sum `inc' [w = `wi'] if `touse', de

        foreach P in 5 10 25 50 75 90 95 {
                local p`P'  = r(p`P')
        }       
       
        local sumwi = r(sum_w)
        local meany = r(mean)
        local vary = r(Var)
        local sdy = r(sd)

        return scalar mean = r(mean)
        return scalar Var = r(Var)
        return scalar sd = r(sd)
        return scalar sumw = r(sum_w)
        return scalar N = r(N)
        return scalar min = r(min)
        return scalar max = r(max)

        foreach p in 5 10 25 50 75 90 95 {
                return scalar p`p' = r(p`p')
        }
        gen double `fi' = `wi' / `sumwi' if `touse'

        gsort -`touse' `inc'

        gen double `py' = (2 * sum(`wi') - `wi' + 1)/(2 * `sumwi' ) if `touse'

        egen double `gini' = sum(`fi'*(2 / `meany') * `py' * (`inc' - `meany')) if `touse'


更详细的code请见http://fmwww.bc.edu/repec/bocode/i/ineqdeco.ado