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help for anovaplot
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Plots of ANOVA fit, including interaction plots 

        anovaplot [, scatter(scatter_options) connected_options plot(plot) ]
                 ]

        anovaplot varlist [, scatter(scatter_options) connected_options
                 plot(plot) ] ]


Description

    anovaplot plots fitted or predicted values from an immediately previous
    one-, two- or three-way anova. By default the data for the response are
    also plotted. In particular, anovaplot can show interaction plots.


Remarks 

    With the first syntax, no varlist is specified.  anovaplot shows the
    response and predicted values on the y axis; the predictor named first in
    the anova command on the x axis; any predictor named second in the anova
    command by separate groups within a twoway plot; and any predictor named
    third in the anova command by separate images using a by() option. Thus
    with this syntax the appearance of the plot, although not the values
    shown, is sensitive to the order in which predictors are specified in the
    anova command.

    With the second syntax, a varlist is supplied, which must be a
    permutation of the predictors previously used. The order of the
    predictors in the varlist is used to determine the form of the graph, as
    above. This permits changing graphs without reissuing the anova command.

    Note especially that the graph format produced by anovaplot is
    appropriate for models with at most one continuous predictor, which
    should always be the predictor named first. With that caveat, anovaplot
    offers a way of showing parallel and diverging regression lines for
    models with one continuous predictor.


Options

    scatter() specifies options of scatter which should be specified to
        control plotting of fitted values.

        To suppress plotting of response data, specify scatter(ms(i)).

        To separate tied values of response, specify scatter(jitter(1)).

    connected_options are options of twoway connected which should be
        specified to control plotting of fitted values.

    plot(plot) provides a way to add other plots to the generated graph; see 
        plot_option.


Examples

    . webuse systolic

    One-way anova: systolic as response on y axis, drug as factor on x axis:

    . anova systolic drug
    . anovaplot

    Two-way anova, no interaction term: systolic as response on y axis,
    disease and drug as factors, with disease on x axis, and levels of drug
    defining separate profiles:

    . anova systolic disease drug
    . anovaplot

    Better to reverse order of predictors:

    . anovaplot drug disease

    Example of interaction term:

    . anova systolic drug disease drug * disease
    . anovaplot

    As above, but no plotting of data:

    . anovaplot, scatter(ms(i))

    Examples with one continuous predictor:

    . sysuse auto
    . decode foreign, gen(Foreign)
    . gen F = substr(Foreign,1,1)

    The continuous predictor is named just after the response:

    . anova price weight foreign, cont(weight)

    (N.B. parallel regression lines)

    . anovaplot, scatter(ms(i) mla(F) mlabpos(0))

    . anova price weight foreign weight*foreign, cont(weight)

    (N.B. diverging regression lines)

    . anovaplot, scatter(ms(i) mla(F) mlabpos(0))


Author

    Nicholas J. Cox, University of Durham, U.K.
    n.j.cox@durham.ac.uk


Acknowledgements 

    Ken Higbee provided very helpful comments.


Also see