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help for dicseg                                  Carlos Gradín (September 2010)
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Overall Segregation indices with optional segregation curve for the case of two
>  groups
(For multigroup cases see localseg)


        dicseg unitvar groupvar [weights] [if exp] [in range] [,
                 format(string) save sc nograph x(string) y(string)
                 xtitle(string) ytitle(string) graph_options(string) ]

        
    fweights, aweights and aweights are allowed; see weights.


Important

    It requires to have matsort, written by Paul Millar, previously
    installed; if not, install it writing in the command line:

        . net install matsort, all from(http://fmwww.bc.edu/RePEc/bocode/m)


Description

    dicseg computes segregation indices across units in a two-groups context.

    Micro data are required (data should not be collapsed by units).

    The first variable unitvar indicates units (ex. occupations, census
    tracts, schools, ....).

    The second variable groupvar identifies dichotomous groups such as gender
    (male vs. female), race (white versus non-white), ...

    If option sc is specified it also draws the segregation curve, and
    creates new variables using x(string) and y(string) options (you can also
    use other graph options).

            x represents the group with the lowest value in groupvar and y
    the group with the highest value.


Reporting

    Segregation indices (See Gradín, 2010):

        . Duncan & Duncan, the Duncan and Duncan (1955) index of
    dissimilarity.


        . KM, the Karmel and Maclachlan (1988) index.


        . GE(c) with c=-1, 0, .10, .25, .50, .75, .90, 1, 2 the family of
    Generalized Entropy measures for different values of the segregation
    sensitivity parameter. GE(1) is Theil index.

            Note: GE(c) is not defined for some c when one group has no
    observations at one or more units. In those cases only well-defined
    indices are reported.


        . Hutchens Sq. root, the Hutchens square root index (Hutchens, 1991,
    2004). Note that it is equivalent to GE(.5)/4


        . Mutual Information, (Frankel and Volij, 2007, 2008) with natural
    logs instead of log(2).


        . Gini, the Gini index.

        Note that Duncan, Gini, and Hutchens are bounded between 0, when
    there is no segregation because both groups have the same distribution
    across units, and 1, when segregation is at its maximum because there is
    no overlap between both distributions.



    Segregation Curve (if option sc is specified): as defined in Duncan and
    Duncan (1955) or Hutchens (1991).


Options

    format(string) to change numeric format

    save to save results

    sc to compute segregation curves

    nograph to do not graph segregation curves (if sc was specified)

    x(string) y(string) to create variables for segregation curves (if sc was
        specified)

    xtitle(string),ytitle(string) title for segregation curves (if sc was
        specified)

    graph_options(string) to change default graph options for segregation
        curve (if sc was specified)


Saved results 

    Matrix:

        r(seg) : segregation indices

Examples 

    . use segdata.dta, clear

    . dicseg occupation white [aw=pwgtp], sc save

    . dicseg occupation2 sex [aw=pwgtp], sc save

    . dicseg occupation white [aw=pwgtp], save sc x(cumnonwhite) y(cumwhite)
        xt(Cumulative proportion of nonwhites) yt(Cumulative proportion of
        whites)

    . dicseg occupation sex [aw=pwgtp], save sc x(cummale) y(cumfemale)
        xt(Cumulative proportion of males) yt(Cumulative proportion of
        females)




Author

    Carlos Gradín <cgradin@uvigo.es>
    Facultade de CC. Económicas
    Universidade de Vigo
    36310 Vigo, Galicia, Spain.


References


    Duncan, Otis D. and Duncan, Bervely (1955), A Methodological Analysis of
        Segregation Indexes, American Sociological Review, 20(2): 210-217.

    Gradín, Carlos (2010),  Conditional occupational segregation of
        minorities in the U.S., Ecineq Working Paper Series 2010-185.

    Hutchens, Robert M. (1991), “Segregation Curves, Lorenz Curves, and
        Inequality in the Distribution of People across Occupations”,
        Mathematical Social Sciences, 21: 31- 51.

    Hutchens, Robert M. (2004), “One Measure of Segregation”, International
        Economic Review 45(2): 555-578.

    Karmel, T. and Maclachlan M. (1988), Occupational Sex Segregation -
        Increasing or Decreasing, Economic Record, 64, 187-195.

Also see

    duncan if installed; hutchens if installed; localseg if installed; seg if
             installed