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help for ^prtab^ - 2Nov2005
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Table of predicted values/probabilities/rates for regression models
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    ^prtab^ rowvar [colvar [supercolvar]] [^if^ exp] [^in^ range],
        [^by(^superrowvar^)^ ^x(^variables_and_values^)^ ^r^est^(^stat^)^
        ^o^utcome^(^string^)^ ^b^rief ^noba^se ^nol^abel ^novar^lbl
        ^con^ditional ^a^ll]

    where

    ^rowvar^, ^colvar^, ^supercolvar^, and ^superrowvar^ are independent variables
        in the previous estimation.

    ^variables_and_values^ is an alternating list of variables and either
        numeric values or mean, median, min, max, upper, lower, previous

    ^stat^ is either mean, median, min, max, upper, lower, previous, grmean
        (group mean), grmedian, grmin, grmax

Description
-----------

After estimating a regression model, ^prtab^ presents a one- to four-way table
of the predicted values (probabilities, rate) for different combinations of
values of independent variable.

The command works with cloglog, cnreg, intreg, logit, mlogit, mprobit, nbreg, 
ologit, oprobit, poisson, probit, regress, slogit, tobit, zinb, zip, ztnb, 
and ztp.

Options
-------

^by(superrowvar)^ specifies numeric variable to be treated as superrow.  Only
    one variable is allowed.

^x()^ sets the values of independent variables for calculating predicted
    values.  The list must alternate variable names and values.  The values
    may be either numeric values or can be mean, median, min, max, previous,
    upper, or lower.  The latter cannot be used if rest() specifies a group
    summary statistic (e.g., grmean).

^rest()^ sets the independent variables not specified in x() to their ^mean^
    (default), ^minimum^, ^maximum^, ^median^ when calculating predicted values.
    ^grmean^ sets these independent variables to the mean conditional on the
    variables and values specified in x(); ^grmedian^, ^grmax^, and ^grmin^ can
    also be used.  If ^prvalue^ has already been run after the last estimate,
    ^previous^ will set unspecified variables to their prior values.  For
    models other than mlogit, ^upper^ and ^lower^ can be used to set independent
    variables to their minimum or maximum depending on which will yield the
    upper or lower extreme predicted value.

^outcome()^ presents results for the specified outcome.  For ordered models or
    mlogit, the default is to provide results for all outcomes (each one in a
    separate table); for count models, the default is to present changes in
    the predicted rate.

^conditional^ for -ztp- and -ztnb-, table with contain conditional predictions
    rather than the default unconditional predictions.

^all^ specifies that any calculations of means, medians, etc., should use
    the entire sample instead of the sample used to estimate the model.

^brief^ and ^nobase^ suppress the base values of x in the output.

^novallbl^ causes the numeric codes to be displayed rather than value labels.

^nolabel^ causes the variable name to be displayed rather than the variable
    label.

Examples
--------

^. probit faculty female fellow phd mcit3 mnas^
^. prtab female fellow mnas^

^. ologit jobclass female fellow pub1 phd^
^. prtab female fellow, x(phd=min)^

^. poisson pub1 female fellow phd enrol^
^. prtab female fellow^
^. prtab female fellow, outcome(0)^

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Authors: J. Scott Long and Jeremy Freese
         www.indiana.edu/~jslsoc/spost.htm
         spostsup@@indiana.edu