update() modifies the stored call and refits. For the two-part formulas
of iop() and iol() the formula. argument may itself be two-part:
. ~ . + x3 | . adds x3 to the outcome equation and keeps the inflation
equation, . ~ . | . + z2 changes only the inflation equation, and a
one-part . ~ . + x3 changes the outcome equation and keeps the inflation
equation (stats::update.formula() alone would fold the | into the
outcome part). Other arguments replace or add to the stored call as in
stats::update().
Usage
# S3 method for class 'iord'
update(object, formula., ..., evaluate = TRUE)Arguments
- object
a fitted
"iord"model.- formula.
changes to the formula, as in
stats::update.formula(), optionally two-part (see Description).- ...
further arguments to the estimator, replacing those in the stored call (
data =,se =,inflate =, ...).- evaluate
if
FALSE, return the modified call unevaluated.
Value
the refitted model (or the modified call). As with every update()
method, the refit evaluates the stored call in the calling environment, so
the data object named in the original call must exist there; a fit
restored with readRDS() in a fresh session can be updated only once that
object is available again (predict(), summary(), and the table methods
need nothing beyond the fit itself).
Examples
data(bp)
m <- oprobit(violence ~ loggdppc + parliament, data = bp)
m2 <- update(m, . ~ . + disaster)
m3 <- update(m, se = "robust")
## two-part formulas: change one equation at a time
mi <- iop(violence ~ loggdppc | parliament, data = bp, inflate = "bottom")
mi2 <- update(mi, . ~ . + disaster | .) # outcome equation only
update(mi, . ~ . | . + disaster, evaluate = FALSE) # the call that would refit
#> iop(formula = violence ~ loggdppc | parliament + disaster, data = bp,
#> inflate = "bottom")