setx {Zelig} | R Documentation |
The setx
command uses the variables identified in
the formula
generated by zelig
and sets the values of
the explanatory variables to the selected values. Use setx
after zelig
and before sim
to simulate quantities of
interest.
x.out <- setx(object, fn = list(numeric = mean, ordered = median, others = mode), data = NULL, cond = FALSE, ...)
object |
the saved output from zelig . |
fn |
a list of functions to apply to three types of variables:
numeric variables are set to their mean by
default, but you may select any mathematical function to apply to
numeric variables.ordered factors are set to their meidan by
default, and most mathematical operations will work on them. If
you select ordered = mean , however, setx will
default to median with a warning.other variables may
only be set to their mode. If you wish to set one of the other
variables to a specific value, you may do so using ...
below. fn = NULL , setx will return all
of the observations without applying any function to the data. |
data |
a new data frame used to set the values of
explanatory variables. If data = NULL (the default), the
data frame called in zelig is used. |
cond |
a logical value indicating whether unconditional
(default) or conditional (choose cond = TRUE ) prediction
should be performed. If you choose cond = TRUE , setx
will coerce fn = NULL and ignore the additional arguments in
... . If cond = TRUE and data = NULL ,
setx will prompt you for a data frame. |
... |
user-defined values of specific variables
overwriting the default values set by the function fn . For
example, adding var1 = mean(data\$var1) or x1 = 12
explicitly sets the value of x1 to 12. In addition, you may
specify one explanatory variable as a range of values, creating one
observation for every unique value in the range of values. |
For unconditional prediction, x.out
is a model matrix based
on the specified values for the explanatory variables. For multiple
analyses (i.e., when choosing the by
option in zelig
,
setx
returns the selected values calculated over the entire
data frame. If you wish to calculate values over just one subset of
the data frame, the 5th subset for example, you may use:
begin{verbatim}
x.out <- setx(z.out[[5]])
end{verbatim}
For conditional prediction, x.out
includes the model matrix
and the dependent variables. For multiple analyses (when choosing
the by
option in zelig
), setx
returns the
observed explanatory variables in each subset.
Kosuke Imai <kimai@princeton.edu>; Gary King <king@harvard.edu>; Olivia Lau <olau@fas.harvard.edu>
The full Zelig manual may be accessed online at http://gking.harvard.edu/zelig.