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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).

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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