*! version 0.5.0 26May2009
help gcmodel: Specify binary model for group comparisons \ 0.5.0 2009-05-26.

Title

gcmodel -- Specifies the independent (RHS) variables for the model;
indicates the sample and method used for computing means used for predictions;
and specifies other details about the model.

Syntax

gcmodel
[if] [in]
,
[ linear(variables)
squared(variables)
cubed(variables)
svy
esample
digits(#)
label(model-label)
details
reset ]

1. rhs-varlist list the non-group RHS variables used in the model.

2. The list does not include the group variables which are specified in gcsetup.

3. If the model includes linear and quadratic (and even cubic) variables (e.g., age
and agesqrd),
rhs-varlist should include the linear variables but not
the squared or cubic variables. Those variables are only specified with the squared
and cubed options. For example, gcmodel x w q, linear(w q) squared(w2 q2) cubed(w3 q3).
The squared and cubic terms must already be in the dataset.

Description

gcmodel specifies the RHS variables in the model, including options for
indicating squared and cubed terms. The command generates variables that are
interactions between the groups indicator variable created by gcsetup
and the RHS variables. It also creates globals containing
the RHS variables needed in an non-interactive model (i.e., group is only included
as a dummy variable) and the interactive model (i.e., coefficients for
all RHS variables can differ by group). These globals make it
simpler to estimate the model. Globals are also created in which the RHS variables
are set equal to the global means (both groups combined), the group 1 means, and
the group 0 means. These can be used in gcprvalue.

Options

digits() is the number of decimal digits to include when creating strings to
pass to gcprvalue as x() options. The default is 3.

label() is a short string to label the current model.

esample indicates that the current estimation should be used when computing means.

svy indicates that survey means should be used.

details produces details on the variables and global variables that are created.

reset resets the globals to null strings.

Note on linear, squared, and cubed optons: these variables must already exist. The linear
variables must be in the varlist. The squared and cubed should not be in the
varlist. These options make it easier to specify values for predictions. For example,
if age and agesquared are in the model, if you hold age at the mean,
you want to hold agesquared at the square of the mean of age
not at the mean of agesquared.

linear() optionally lists variables from varlist that
have squares and/or cubes in the model (e.g., age, agesqrd, agecubd).

squared() lists variables that are the squares of the variables specified
with the linear() option.

cubed() lists variables that are the cubes of the variables specified
with the linear() option.

Examples

. gcmodel...

Saved globals and variables

Globals

a ...to be added

b ...to be added

Variables

a ...to be added

b ...to be added