logLik.kppm

0th

Percentile

Log Likelihood and AIC for Fitted Cox or Cluster Point Process Model

Extracts the log Palm likelihood, deviance, and AIC of a fitted Cox or cluster point process model.

Keywords
models, spatial
Usage
# S3 method for kppm
logLik(object, ...)
# S3 method for kppm
AIC(object, …, k=2)
# S3 method for kppm
extractAIC(fit, scale=0, k=2, …)
# S3 method for kppm
nobs(object, ...)
Arguments
object,fit

Fitted point process model. An object of class "kppm".

Ignored.

scale

Ignored.

k

Numeric value specifying the weight of the equivalent degrees of freedom in the AIC. See Details.

Details

These functions are methods for the generic commands logLik, extractAIC and nobs for the class "kppm".

An object of class "kppm" represents a fitted Cox or cluster point process model. It is obtained from the model-fitting function kppm.

These methods apply only when the model was fitted by maximising the Palm likelihood (Tanaka et al, 2008) by calling kppm with the argument method="palm".

The method logLik.kppm computes the maximised value of the log Palm likelihood for the fitted model object.

The methods AIC.kppm and extractAIC.kppm compute the Akaike Information Criterion AIC for the fitted model based on the Palm likelihood (Tanaka et al, 2008) $$ AIC = -2 \log(PL) + k \times \mbox{edf} $$ where \(PL\) is the maximised Palm likelihood of the fitted model, and \(\mbox{edf}\) is the effective degrees of freedom of the model.

The method nobs.kppm returns the number of points in the original data point pattern to which the model was fitted.

The R function step uses these methods.

Value

logLik returns a numerical value, belonging to the class "logLik", with an attribute "df" giving the degrees of freedom.

AIC returns a numerical value.

extractAIC returns a numeric vector of length 2 containing the degrees of freedom and the AIC value.

nobs returns an integer value.

References

Tanaka, U. and Ogata, Y. and Stoyan, D. (2008) Parameter estimation and model selection for Neyman-Scott point processes. Biometrical Journal 50, 43--57.

See Also

kppm, logLik.ppm

Aliases
  • logLik.kppm
  • AIC.kppm
  • extractAIC.kppm
  • nobs.kppm
Examples
# NOT RUN {
  fit <- kppm(redwood ~ x, "Thomas", method="palm")
  nobs(fit)
  logLik(fit)
  extractAIC(fit)
  AIC(fit)
  step(fit)
# }
Documentation reproduced from package spatstat, version 1.59-0, License: GPL (>= 2)

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