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help for concindexi 
   (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 covariance 
> formulae.


    concindexi [varlist] [if] [in] [weight] [ , welfarevar(varname)
    format(format) curve convenient clean }

 
    where :

    welfarevar is the welfare variable - not optional - ,

    format is the format type used to display results,

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

    curve is to graph lorenz curve for each indicator,

    convenient is to use in addition the convenient regression method to
    compute the concentration index.


Description

    concindexi computes the concentration index on individual (micro) data.
    See work by Wagstaff and Kakwani.


Formulas

    The concentration index 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 a "covariance" or "formula" method:


                             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

    . concindexi has_water has_elec, welf(quint)

    . concindexi has_water has_elec, welf(quint) cu cl)

    . concindexi has_water [aw=weight], we(quint) co by(urbrur)

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


Saved Results

    Concentration indices are saved in matrice r(CII).


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 concindexg, ineqdeco, inequal, povdeco, ineqerr if
    installed.


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