logLik.ergm: A 'logLik' method for 'ergm' fits.

Description Usage Arguments Value Functions References See Also Examples

View source: R/logLik.ergm.R

Description

A function to return the log-likelihood associated with an ergm fit, evaluating it if necessary. If the log-likelihood was not computed for object, produces an error unless eval.loglik=TRUE.

Usage

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## S3 method for class 'ergm'
logLik(
  object,
  add = FALSE,
  force.reeval = FALSE,
  eval.loglik = add || force.reeval,
  control = control.logLik.ergm(),
  ...
)

## S3 method for class 'ergm'
deviance(object, ...)

## S3 method for class 'ergm'
AIC(object, ..., k = 2)

## S3 method for class 'ergm'
BIC(object, ...)

Arguments

object

An ergm fit, returned by ergm.

add

Logical: If TRUE, instead of returning the log-likelihood, return object with log-likelihood value (and the null likelihood value) set.

force.reeval

Logical: If TRUE, reestimate the log-likelihood even if object already has an estiamte.

eval.loglik

Logical: If TRUE, evaluate the log-likelihood if not set on object.

control

A list of control parameters for algorithm tuning, typically constructed with control.logLik.ergm(). Its documentation gives the the list of recognized control parameters and their meaning. The more generic utility snctrl() (StatNet ConTRoL) also provides argument completion for the available control functions and limited argument name checking.

...

Other arguments to the likelihood functions.

k

see help for AIC().

Value

The form of the output of logLik.ergm depends on add: add=FALSE (the default), a logLik object. If add=TRUE (the default), an ergm object with the log-likelihood set.

As of version 3.1, all likelihoods for which logLikNull is not implemented are computed relative to the reference measure. (I.e., a null model, with no terms, is defined to have likelihood of 0, and all other models are defined relative to that.)

Functions

References

Hunter, D. R. and Handcock, M. S. (2006) Inference in curved exponential family models for networks, Journal of Computational and Graphical Statistics.

See Also

logLik, logLikNull, ergm.bridge.llr, ergm.bridge.dindstart.llk

Examples

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# See help(ergm) for a description of this model. The likelihood will
# not be evaluated.
data(florentine)
## Not run: 
# The default maximum number of iterations is currently 20. We'll only
# use 2 here for speed's sake.
gest <- ergm(flomarriage ~ kstar(1:2) + absdiff("wealth") + triangle, eval.loglik=FALSE)

gest <- ergm(flomarriage ~ kstar(1:2) + absdiff("wealth") + triangle, eval.loglik=FALSE,
             control=control.ergm(MCMLE.maxit=2))
# Log-likelihood is not evaluated, so no deviance, AIC, or BIC:
summary(gest)
# Evaluate the log-likelihood and attach it to the object.

# The default number of bridges is currently 20. We'll only use 3 here
# for speed's sake.
gest.logLik <- logLik(gest, add=TRUE)

gest.logLik <- logLik(gest, add=TRUE, control=control.logLik.ergm(bridge.nsteps=3))
# Deviances, AIC, and BIC are now shown:
summary(gest.logLik)
# Null model likelihood can also be evaluated, but not for all constraints:
logLikNull(gest) # == network.dyadcount(flomarriage)*log(1/2)

## End(Not run)

ergm documentation built on July 27, 2021, 5:07 p.m.