surveillance (version 1.12.1)

twinstim_update: update-method for "twinstim"

Description

Update and (by default) re-fit a "twinstim". This method is especially useful if one wants to add the model environment (which is required for some methods) to a fitted model object a posteriori.

Usage

## S3 method for class 'twinstim':
update(object, endemic, epidemic,
       control.siaf, optim.args, model,
       ..., use.estimates = TRUE, evaluate = TRUE)

Arguments

object

a previous "twinstim" fit.

endemic, epidemic

changes to the formulae -- see update.formula and twinstim.

control.siaf

a list (see twinstim) to replace the given elements in the original control.siaf list. If NULL, the original list of control arguments is removed from the call, i.e.,

optim.args

see twinstim. If a list, it will modify the original optim.args using modifyList.

model

see twinstim. If this is the only argument to update, re-fitting is cleverly circumvented. Enriching the fit by the model environment is, e.g., required for

...

Additional arguments to the call, or arguments with changed values. If start values are specified, they need to be in the same format as in the original call object$call$start, which is either a named list of named nu

use.estimates

logical indicating if the estimates of object should be used as initial values for the new fit (in the start argument of twinstim). Defaults to TRUE.

evaluate

If TRUE (default), evaluate the new call else return the call.

Value

• If evaluate = TRUE the re-fitted object, otherwise the updated call.

See Also

update.default

Examples

data("imdepi")
data("imdepifit")

## add another epidemic covariate (but fix siaf-parameter for speed)
imdepifit2 <- update(imdepifit, epidemic = ~. + log(popdensity),
                     optim.args = list(fixed="e.siaf.1"))
  
## compare by AIC
AIC(imdepifit, imdepifit2)