Calculate Pseudo-R-Squared for Point Process Model

Description

Given a fitted point process model, calculate the pseudo-R-squared value, which measures the fraction of variation in the data that is explained by the model.

Usage

  pseudoR2(object, ...)

  ## S3 method for class 'ppm'
pseudoR2(object, ...)

  ## S3 method for class 'lppm'
pseudoR2(object, ...)

Arguments

Details

The function pseudoR2 is generic, with methods for fitted point process models of class "ppm" and "lppm".

This function computes McFadden's pseudo-Rsquared

R^2 = 1 - D/D0

where D is the deviance of the fitted model object, and D0 is the deviance of the null model (obtained by refitting object using the trend formula ~1). Deviance is defined as twice the negative log-likelihood or log-pseudolikelihood.

Value

A single numeric value.

Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

Rolf Turner r.turner@auckland.ac.nz

and Ege Rubak rubak@math.aau.dk

See Also

deviance.ppm, deviance.lppm.

Examples

  fit <- ppm(swedishpines ~ x+y)
  pseudoR2(fit)