{smcl}
{* 14sep2001/23jul2002}{...}
{hline}
help for {hi:regplot7}
{hline}
{title:Plots of regress or similar fit}
{p 8 16}{cmd:regplot7} [{cmd:,} {it:graph_options}
{cmdab:sep:arate(}{it:varname}{cmd:)} ]
{p 8 16}{cmd:regplot7} {it:varname} [{cmd:,} {it:graph_options}
{cmdab:sep:arate(}{it:varname}{cmd:)} ]
{title:Description}
{p}{cmd:regplot7} plots fitted or predicted values from an immediately previous
{cmd:regress} or similar command. By default the data for the response are also
plotted.
{title:Remarks}
{p}With the first syntax, no varname is specified. {cmd:regplot7} shows the
response and predicted values on the y axis and the covariate named first in
the {cmd:regress} or similar command on the x axis. Thus with this syntax the
plot shown is sensitive to the order in which covariates are specified in the
estimation command.
{p}With the second syntax, a varname is supplied, which may name any numeric
variable. This is used as the variable on the x axis. This permits changing
graphs without reissuing the estimation command.
{p}Thus in practice {cmd:regplot7} is most useful when the fitted values are a
smooth function of the variable shown on the x axis, or a set of such functions
given also one or more dummy variables as covariates. However, other
applications also arise, such as plotting observed and predicted values
from a time series model versus time.
{p}In more technical detail: {cmd:regplot7} plots
{p}1. both a single dependent or response variable as specified in
{cmd:e(depvar)} and whatever single variable is calculated by the default of
{cmd:predict} on the y axis, which makes sense whenever those variables are on
the same scale;
{p}2. either the {it:varname} specified or what names the first column of
{cmd:e(b)} on the x axis, which makes sense whenever {cmd:graph} can
understand that as specifying the x axis.
{p}If your estimation results do not meet these specifications, you are likely
to get either bizarre results or an error message. Note in particular
that {it:varname} must be specified after {cmd:nl}.
{p}Time series operators are allowed.
{p}The plot is restricted to the estimation sample.
{p}{cmd:regplot7} is a renamed clone of {cmd:regplot} 1.2.0 which is for
Stata 7. Stata 8 users should use {cmd:regplot} 2.0.0 or later.
{title:Options}
{p 0 4}
{it:graph_options} are options of {cmd:graph, twoway}.
{p 4 4}
The defaults include {cmd:connect()} of {cmd:.} for data and {cmd:s} for each
subset of predicted values.
{p 4 4}
To suppress plotting of response data, specify {cmd:i} as the first
{cmd:symbol} to be shown.
{p 0 4}
{cmd:separate(}{it:varname}{cmd:)} specifies that predictions are to be
shown separately for different categories of {it:varname}. This will be
most appropriate when the categories of {it:varname} are associated
with one or more dummy or indicator variables.
{p 0 4}
Note that {cmd:by(}{it:varname}{cmd:)} may be employed as usual
with {cmd:regplot7} and it also may be combined with {cmd:separate()}.
{title:Examples}
{p 4 8}{inp:. use auto}
{p}continuous variables only:
{p 4 8}{inp:. regress mpg weight}
{p 4 8}{inp:. regplot7}
{p 4 8}{inp:. gen weightsq = weight^2}
{p 4 8}{inp:. regress mpg weight weightsq}
{p 4 8}{inp:. regplot7}
{p 4 8}(N.B. {inp: weight} shown on x axis in both cases)
{p}categorical variable also:
{p 4 8}{inp:. regress mpg weight foreign}
{p 4 8}{inp:. regplot7, sep(foreign) tr(1)}
{p 4 8}{inp:. regress mpg weight weightsq foreign}
{p 4 8}{inp:. regplot7, sep(foreign) tr(1)}
{p 4 8}{inp:. regplot7, by(foreign)}
{p 4 8}{inp:. regplot7, by(foreign) sep(foreign) tr(1) total}
{p 4 8}{inp:. gen fw = foreign * weight}
{p 4 8}{inp:. regress mpg weight foreign fw}
{p 4 8}{inp:. regplot7, sep(foreign) tr(1)}
{p}commands other than {cmd:regress}:
{p 4 8}{inp:. logit foreign weight}
{p 4 8}{inp:. regplot7}
{p 4 8}{inp:. glm mpg weight foreign, link(log)}
{p 4 8}{inp:. regplot7, sep(foreign) tr(1)}
{p}fit an AR(1) plus trend model to time series:
{p 4 8}{inp:. regress ERvol L.ERvol date}
{p 4 8}{inp:. regplot7 date}
{title:Author}
Nicholas J. Cox, University of Durham, U.K.
n.j.cox@durham.ac.uk
{title:Acknowledgements}
Ken Higbee and Kit Baum provided very helpful comments.
{title:Also see}
{p 0 19}On-line: help for {help regress}, {help graph}, {help regdiag},
{help anovaplot} (if installed), {help sparl} (if installed)
{p_end}
{p 1 19}Manual: {hi: [U] 21 Programming Stata}
{p_end}