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help for iop
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 Dissimilarity index for inequality of opportunity when the outcome is dichotom
> ous


        iop depvar indepvars [if] [in] [,bootstrap(int) decomposition
                 groups(varname (max=1)) propt(str) bootopt(str)]


Description

    This ado-file performs an analysis of inequality of opportunity in the
    access of depvar based on the methodology proposed by Paes de Barros et
    al. (2008).  The main idea of the analysis is to capture the importance
    of indepvars in explaining differences in depvars, where indepvars are
    generally characteristics beyond individuals' control, thus they should
    not explain depvar in a situation of equality of opportunity.

    The analysis is performed in the following way. First a simple probit
    model of depvar on indepvars is performed. In a second step the
    dissimilarity index is computed with the predicted values of the probit
    estimation. The idea is that all differences in these predicted values
    must be due to characteristics beyond individuals' control, thus they
    represent inequality of opportunity. A detailed description along with an
    application can be found in Soloaga & Wendelspiess Chávez Juárez (2012)
    Alternative routines are are mentioned below.

Options

    bootstrap(int) Use this option to include bootstrap confidence intervals
        of the dissimilarity index by indicating the desired amount of
        repetitions. The default value is 0, resulting in no computation of
        bootstrap confidence intervals.

    decomposition This option includes a decomposition of the computed
        dissimilarity index. The same method is used and all but one variable
        is set to the average when computing the predicted values. Beware of
        the fact that the sum of these estimates does not necesarily yield to
        the total effect.

    groups(varname (max=1)) By activating this option, the decomposition
        across groups is perfomed. Indicate the categorical variable
        containing a definition of the groups.

    propt(str) Use this option to include special options in the probit
        estimation. Just write your probit options normally and they are
        transmitted to the probit estimation in the script.

    bootopt(str) Use this option to include special options in the bootstrap
        sampling. Just write your bootstrap options normally and they are
        transmitted to the bsample command in the script.


Example

    iop access_school education_father family_income indigenous, decomp
        boot(100)

    This example would calculate the inequality of opportunity in the access
    to schooling based on three explanatory variables: father's education,
    the family income and a dummy for indigenous people. Additionally the
    index is also computed for each of the independent variables individually
    and a bootstrap confidence interval for the main index is computed using
    100 iterations.


Alternative routines
    An alternative routine to estimate the dissimilarity index is hoi.
    Compared to the current version of iop it performs almost the same
    calculation regarding dissimilarity index. Differences between the two
    routines include the estimation of the conditional probability (hoi uses
    logit instead of probit) and mainly the options the routine offers to the
    user. For inference, hoi should be preferred, since it computes not only
    the bootstrap standard errors but also the analytical standard errors.

Future developments
    The routine iop will be developped further. We plan to include several
    recent contributions to the measurement of inequality of opportunity in
    order to provide a routine that is able to deal not only with dichotomous
    variables, but also with continuous variables. If you have particular
    suggestions, please let us know. Otherwise, update the routine by typing
    scc install iop, replace

Author

    Florian Wendelspiess Chávez Juárez & Isidro Soloaga:
    florian@chavezjuarez.com

References
    Soloaga, Isidro and Florian Wendelspiess Chávez Juárez (2012). El comando
    iop para estimar desigualdad cuando el indicador es binario.  Forthcoming
    in: Aplicaciones en Economía y Ciencias Sociales con Stata. Stata Press.

    Paes de Barros, R and M. de Carvalho (2008). Measuring Inequality of
    Opportunity in Latin America and the Caribbean"

    Paes de Barros, R and M. de Carvalho and S. Franco (2007). Preliminary
    Notes on the Measurement of Socially-Determined Inequality of Opportunity
    when the Outcome is Discrete". IPEA, Rio de Janeiro

    Paes de Barros, Ricard and Francisco H. G. Ferreira and José R. Molinas
    Vega and Jaime Saavedra Chanduvi.  Measuring Inequality of Opportunities
    in Latin America and the Caribbean-Inequality. The World Bank. 2009

    Soloaga, Isidro and Florian Wendelspiess Chávez Juárez. Desigualdad de
    Oportunidades: aplicaciones al caso de México. IN: Movilidad Social en
    México: Población, desarrollo y crediciento, edited by Julio Serrano
    Espinosa and Florencia Torche. Centro de Estudios Espinosa Yglesias.
    Mexico City. 2010.