[R] margins, saving() -- Save margins results to a dataset
margins [marginlist] [if] [in] [weight] [, saving(filename, ...)
margins, saving() saves a dataset containing the statistics reported in
Each observation in the margins, saving() dataset corresponds with a row
in the output table.
The following variables are always present:
_deriv identifies the variable that the margin values were
differentiated with respect to. The values in _deriv are labeled
with the independent variables specified in the dydx() options;
otherwise, _deriv contains all missing values. For factor
variables, the factor level is contained in the label.
_term identifies the factor variables participating in the marginlist
term associated with the estimated margin value. The values in
_term are labeled with a list of the names of the factor
variables present in the terms specified in marginlist; the grand
margin is labeled "_cons".
_predict identifies the predict() option associated with the
estimated margin value. The values in _predict are labeled with
the predict() option. _predict contains missing values when the
expression() option is specified.
The _dta[k_predict] characteristic identifies how many predict()
options were specified or implied. This characteristic is empty
when the expression() option is specified with an expression that
contains more than just a reference to an equivalent predict()
_margin contains the estimated margin values.
_se contains the estimated standard errors of the estimated margin
_statistic contains the value of the z (or t) statistic for testing
the margin values against zero.
_pvalue contains the observed significance level for a two-sided test
of the marginal values against zero.
_ci_lb and _ci_ub contain the confidence interval limits for the
A variable with the _m prefix is present for each unique factor variable
specified in marginlist.
_m# contains the levels of the #th unique factor variable in
marginlist, identifying the level corresponding with the
estimated margin value. _m# is missing if the associated factor
variable is not in the list of factor variables corresponding
with the term for a given estimated margin value.
The _m#[varname] characteristic identifies the factor variable
that _m# corresponds to.
The _dta[margin_vars] characteristic contains the names of the
factor variables associated with the _m# variables.
A variable with the _at prefix is present for each unique independent
variable in the model when one or more independent variables is fixed
because of options atmeans, asbalanced, or at().
_at# contains the value at which the #th independent variable was
fixed. For factor variables, _at# contains the .b missing value
if the factor variable was treated as balanced. _at# contains
the .o missing value if the variable was left as observed.
The _at#[varname] characteristic identifies the independent
variable that _at# corresponds to. The _at#[stats]
characteristic identifies the statistic at which the variable was
set; there is one statistic for each at() option. In addition to
the statistics documented with the at() option, the following
identifiers are used when one or multiple values are specified in
the at() option: value and values.
The _dta[at_vars] characteristic contains the names of the
independent variables associated with the _at# variables.
The _dta[k_at] characteristic identifies how many at() options
were specified/implied. The _dta[atopt#] characteristic
identifies the specification of the #th at() option. The
_dta[atstats#] characteristic identifies the specification
attached to the variables in the #th at() option.
There will also be an _at variable that identifies groups of margin
values associated with patterns in the _at# variables and an
_atopt variable that identifies groups of margin values
associated with each at() option.
A variable with the _by prefix is present for each variable specified in
the over() and within() options.
_by# identifies the group level of the #th grouping variable
associated with the estimated margin value.
The _by#[varname] characteristic identifies the group variable
that _by# corresponds to.
The _dta[by_vars] characteristic contains the names of the group
variables associated with the _by# variables. The _dta[over]
characteristic identifies the over() variables, and the
_dta[within] characteristic identifies the within() variables.