-------------------------------------------------------------------------------
help for classplot
-------------------------------------------------------------------------------

Graphical comparison of predicted probability and empirical values of outcome a
> fter a binary response model 

        classplot [ , xcategories(integer) ycategories(integer) plotall
                 twoway_options ]


Description

    classplot draws a comparison of predicted probability and empirical
    values of outcome after a binary response model like logit or probit. It
    is an extension of estat classification.  classplot provides a simple way
    to search for cut-off values.

    Users may chose the number of vertical aligned symbols and the number of
    categories of predicted probability. It is possible to change
    twoway_options.

Remarks 

    The default graph plots all cases if the maximum number in a
    probability-category is smaller than 20. If the number exceeds 20 cases
    each symbol represents more than one case (e.g. no case will be omitted).
    In this case the maximum number is shown in a note. In fact the first and
    the last symbol of a probability category may represent 1 to max. no.
    cases, symbols in between represent definitively max. no. cases.

    classplot may be computationally expensive (e.g. cases*xcat*ycat
    calculations are performed).

Options 

    xcategories(integer) Number of categories of predicted probability.
        xcat(integer) needs an integer from 2 to 100 as an argument (default
        25).

    ycategories(integer) Number of (vertical aligned) symbols in each
        category of predicted probability.  xcat(integer) needs an integer
        from 1 to 100 as an argument (default 20).

    plotall forces classplot to plot all cases as unique symbols. This option
        is not recommended with large (>100 cases) datasets, because one
        won't be able to disciminate plotsymbols. plotall overrides the
        ycat(#) option.

    twoway_options refers to options of twoway.

Examples

Default usage:

    . sysuse auto

    . logit foreign price weight mpg

    . classplot

 To produce a "clean" plot with all cases:

    . classplot , plotall legend(off) subtitle("") title("") xtitle("")
        ytitle("")

 Compare two plots (100 vs. 1000 symbols):

    . classplot, ycat(10) xcat(10) name(cp_10x10) noshow

    . classplot, ycat(100) xcat(100) name(cp_100x100) noshow

    . graph combine cp_10x10 cp_100x100 , rows(2)

Acknowledgements

Future versions of classplot may be byable accept if-statements and
fweights if requested.

Author

    Lars E. Kroll,  email
    http://www.lkroll.de

Also see

    On-line:  help for graph_twoway, logit, probit, logit postestimation