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help for concindexg 
   (Amadou Bassirou DIALLO: AFTPM, The World Bank and CERDI, Univ. of Auvergne)
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Estimation of the Concentration Index based on Kakwani and Wagstaff formulae.


    concindexg [varlist] [if] [in] [weight] [ , welfarevar(varname) drop
    format(format) splitvars(varlist) se clean }

 
    where :

    welfarevar is the welfare variable - not optional - ,

    drop is to clean the welfare indicator from missings,

    format is the format type,

    splitvars is to generate dummies from categorical variables,

    se is to compute also standard errors of the concentration index,

    clean is to erase matrices and scalars created by the program.


Description

    concindexg computes the concentration index on grouped data. See work by
    Wagstaff and Kakwani.


Formulas

    The concentration index, in the case of no standard deviations is
    computed as:

                  C = 2 cov(yi,Ri) / µ


    yi is the individual i's indicator variable (e.g. health status),

    µ its mean

    Ri his fractional rank in the socioeconomic distribution

    Standard errors of C are obtained by:


                             1   1        2             2
                  Var(C) =   - [ - sum (a   ) - (1 + C)   ]
                             n   n 

    where :


                     yi
                  a = -  ( 2 Ri - 1 - C) + 2 - qi-1 - qi
                      µ

    and :

                       1
                  qi = - sum(yi)
                       µn 

    is the ordinate of the concentration curve L(p), and q0 = 0.

 
Examples

    . concindexg has_water has_elec, welf(quint)

    . concindexg has_water has_elec, welf(quint) dr se cl)

    . concindexg has_water [aw=weight], we(quint) se by(urbrur)

    . concindexg var1 var2 [aw=weight], we(quint) f(%9.2f)


Saved Results

    Concentration indices are saved in matrice r(CIG).


Author

    Amadou Bassirou DIALLO, AFTPM, The World Bank -and- CERDI, Univ. of
    Auvergne (France).

    Email: adiallo5@worldbank.org, adiallo5@gmail.com


Note

    This program has been initially developped to use the Demographic and
    Health Surveys (DHS).


Also see

    Online:  help for concindexi, ineqdeco, inequal, povdeco, ineqerr if
    installed.


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