help paragr

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Title

    paragr -- Parallel graphing of a coefficient across different equations


Syntax

    paragr variable [, options]


Description

    paragr provides a fast and easy way to compare a coefficient across
        different equations within an estimation.

    It can used to visualize the parallel assumption of ordered logit or
        the equality of coefficients for quantile regression, etc.

    By default paragr plots a scatter graph. A quadratic fitted line
        (qfit) can be superimposed.

    Twoway graph options can be specified for the entire graph, or
        separately for the scatter graph or for the qfit graph.


Options

        +------+
    ----+ Main +-------------------------------------------------------------

    scatter( ) standard options for scatter graph. Use this to set color,
            range, etc

    qfit a quadratic fitted line is superimposed.

    qfit( ) standard options for qfit graph. Use this to set color,
            range, etc

    gen( ) a prefix for saving the plot points as variables.

    click here for a list of twoway options, including:

        nodraw suppress the display of graph

        saving( ) save as a Stata graph

        name(name[, replace]) specifies the name of the graph


Examples

    * reg3
    sysuse auto, clear
    reg3 (price weight rep78) (price weight rep78 mpg) (price weight
        rep78 mpg headroom) (price weight rep78 mpg headroom length)
    paragr rep78, xtitle(Equation) gen(reg3_) saving(mygraph)


    * sqreg
    sysuse auto, clear
    sqreg price mpg rep78 headroom length, q(.10 .20 30 .40 .50 .60 .70
        .80 .90) reps(25)
    paragr rep78, qfit


    * Unconstrained gologit
    sysuse auto, clear
    egen money=cut(price), group(5)
    gologit money headroom mpg weight length turn displacemen
    paragr displacement


    * constrained gologit2 from ssc (need Stata 8.2 or better)
    sysuse auto, clear
    egen money=cut(price), group(5)
    gologit2 money headroom mpg weight length turn displacement, auto
    paragr weight, qfit ytitle(odds ratios) xtitle(cut)


Remarks

    qfit requires at least two equations.

    Coefficient values goes on the y-axis.


Acknowledgement

    Nick Cox provided detailed and helpful suggestions.


Author

    Roy Wada
    roywada@hotmail.com