ergm.degeneracy: Checks an ergm Object for Degeneracy

Description

The ergm.degeneracy function checks a given ergm object for degeneracy by computing and returning the instability value of the model and the value of the log-likelihood function at the maximized theta values

Usage

ergm.degeneracy(object, control = object$control, 
                fast = TRUE, test.only = FALSE, 
                verbose = FALSE)

Arguments

object

an ergm object

control

the list of control parameters as returned by control.ergm; default=control.ergm()

fast

whether the degeneracy check should be "fast", i.e to sample changeobs(?) when there are > 100, rather than use all changeobs; default=TRUE

test.only

whether to silence printing of the model instability calculation (T or F); this parameter is ignored if the instability > 1; default=FALSE

verbose

whether to print a notification when 'object' is deemed degenerate (T or F); default=FALSE

Value

returns the original ergm object with 2 additional components:
- degeneracy.value: the instability of the model
- degeneracy.type : a 2-element vector containing
  - loglikelihood: the value of the log-likelihood function corresponding to 'theta'; if degenerate, this is a vector of Inf
- theta : the vector of theta values found through maximixing the log- likelihood; if degenerate, this is 'guess'