gdxis: Create globals for specifying prvalue and logit
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Global variables are created that make it simple to specify the values
of the RHS variables to use when computing predicted probabilities for
group comparisons using -gdprdif-. These globals set RHS variable to
equal group means or grand means for models with our without interactions.
Means can optionally be computed using svy commands.

This program must be run after -gdset-.

SYNTAX

gdxis <varlist> [if] [in], [ label(string) svy NOEsample Details
    digits(#) LINear(varlist) SQUared(varlist) CUBed(varlist)  debug]

OPTIONS

varlist         The variables to include in the x() string.
if & in         Conditions to select the sample for computing means.
label(string)   Label that is place in the global gislabel.
svy             Use svy means computed by svy: means.
noesample       Use all cases in memory, not the estimation sample.
digits(#)       Round the means to this many digits; default is 3.
reset           Reset globals and exit.
debug           Show debugging output.
details         Show detailed output.

If your model has squared and/or cubic terms, values for these variables
are computed based on the mean for the linear term (e.g., instead of
takeing the mean of x-squared, the mean of x is squared).

linear()    Name of linear variable from a set of linked quadratic variables
squared()   Name of squared variable from a set of linked quadratic variables
cubed()     Name of cubic variable from a set of linked quadratic variables

GLOBALS

xis:       RHS variables set to grand means.
xismn0:    RHS variables set to group 0 means.
xismn1:    RHS variables set to group 1 means.

xisg0:     RHS by group 0 interaction variables set to grand means.
xisg0mn0:  RHS by group 0 interaction variables set to group 0 means.
xisg1:     RHS by group 1 interaction variables set to grand means.
xisg1mn1:  RHS by group 1 interaction variables set to group 1 means.

rhsnoint:   Names of group variable and all RHS variables
rhsg0:      Names of group 0 indicator and g0 by RHS interactions
rhsg1:      Names of group 1 indicator and g1 by RHS interactions

EXAMPLE

. use group_ten01, clear
. gdaccum2, matrix(PrTenure) reset
. gdset2, gvar(male) g0var(f0) g1var(m1) ///
>     g0label(women) g1label(men) details
. gdgen2 year art prestige, details
. logit tenure $gvar
. gdprdif2, constant matrix(PrTenure) rownm(M1_Obs1)
. logit tenure $g0var $g1var, nocon
. gdprdif2, matrix(PrTenure) rownm(M1_Obs2)

. gdxis2 year art prestige, details label(TEST)

Label: TEST

Globals for RHS variables without interactions:

    $xis (grand means):        year=4.330 articles=7.209 prestige=2.634
    $xismn0 (group 0 means):   year=4.529 articles=7.556 prestige=2.645
    $xismn1 (group 1 means):   year=4.207 articles=6.996 prestige=2.627

Globals for group 0 by RHS interaction variables:

    $xisg0 (grand means):       f0year=4.330 f0articles=7.209 f0prestige=2.634
    $xisg0mn0 (group 0 means):  f0year=4.529 f0articles=7.556 f0prestige=2.645

Globals for group 1 by RHS interaction variables:

    $xisg1 (grand means):       m1year=4.330 m1articles=7.209 m1prestige=2.634
    $xisg1mn1 (group 1 means):  m1year=4.207 m1articles=6.996 m1prestige=2.627

svy means are not being used.

Variable names:

    $gvar:        male
    $g0var:       f0
    $g1var:       m1
    $g0label:     women
    $g1label:     men

RHS variable lists:

    $rhsg0:       f0 f0year f0articles f0prestige
    $rhsg1:       m1 m1year m1articles m1prestige
    $rhsnoint:    male year articles prestige

RHS group variables set to 1

    $gis:         male=1
    $gisg0:       f0=1
    $gisg1:       m1=1

HISTORY

2008-01-26
exit