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help for dagumpred                              Stephen P. Jenkins (April 2004)
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Prediction following fitting of a Dagum distribution

        dagumpred [if exp] [in range] [ , aval(value list1) bval(value list2)
                 pval(value list3) abpval(value list) poorfrac(#)
                 cdf(cdfname) pdf(pdfname) ]

Description

    dagumpred calculates statistics summarizing a 3 parameter Dagum
    distribution which has been fitted using dagumfit to sample observations
    on variable var.  dagumpred is usually used when the model parameters
    have been specified as functions of covariates in dagumfit . Users
    specify particular covariate values here, which implies values of the
    model parameters, and thence statistics can be calculated, together with
    the fitted c.d.f. and p.d.f. The statistics produced by default are
    selected quantiles, cumulative shares of total income at percentiles
    (i.e. the Lorenz curve ordinates), the mode, mean, standard deviation,
    variance, half the coefficient of variation squared, Gini coefficient,
    and quantile ratios p90/p10, p75/p25. The command can be repeated using a
    different set of covariate values.

Options

    aval(value list1), bval(value list2), and pval(value list3) are required
        if the original model was estimated with covariates. In this case,
        the user must specify a value for each covariate included in the
        original model, and in the same order. The last element in each
        equation must always be 1 (corresponding to the intercept term).
        Where there is more than one element per equation, they must be
        separated by commas.

    abpval(value list) can be used instead of the previous option if the same
        covariates appeared in each parameter equation.

    poorfrac(#) displays the estimated proportion with values of var less
        than the cut-off specified by #.

    cdf(cdfname) creates a new variable cdfname containing the estimated
        Dagum c.d.f. value F(x) for each x.

    pdf(pdfname) creates a new variable pdfname containing the estimated
        Dagum p.d.f. value f(x) for each x.

        Options if and in have an effect only if options cdf or pdf are
        specified.


Saved results

    The following are saved, some contingent on the relevant options being
    specified:

    e(bba), e(bbb), and e(bbp) are the estimated Dagum parameters. (If the
    original model included no covariates, these contain the parameters
    originally estimated. If covariates were included, these contain the
    parameters evaluated at the values of the covariates specified here.)

    e(cdfvar) and e(pdfvar) are the variable names specified for the c.d.f.
    and the p.d.f.

    e(mode), e(mean), e(var), e(sd), e(i2), and e(gini) are the estimated
    mode, mean, variance, standard deviation, half coefficient of variation
    squared, Gini coefficient. e(pX), and e(LpX) are the quantiles, and
    Lorenz ordinates, where X = {1, 5, 10, 20, 25, 30, 40, 50, 60, 70, 75,
    80, 90, 95, 99}.


Examples

    . dagumfit x

    . dagumpred

    . dagumfit x, a(age sex) b(age sex) p(age sex)

    . dagumpred, a(40,2,1) b(40,2,1) p(40,2,1)

    . dagumpred, abp(50,2,1) poorfrac(100)


Author

    Stephen P. Jenkins <stephenj@essex.ac.uk>, Institute for Social and
    Economic Research, University of Essex, Colchester CO4 3SQ, U.K.


Also see

dagumfit