spatstat (version 1.48-0)

anova.lppm: ANOVA for Fitted Point Process Models on Linear Network

Description

Performs analysis of deviance for two or more fitted point process models on a linear network.

Usage

"anova"(object, ..., test=NULL)

Arguments

object

A fitted point process model on a linear network (object of class "lppm").

...

One or more fitted point process models on the same linear network.

test

Character string, partially matching one of "Chisq", "F" or "Cp".

Value

An object of class "anova", or NULL.

Errors and warnings

Details

This is a method for anova for fitted point process models on a linear network (objects of class "lppm", usually generated by the model-fitting function lppm).

If the fitted models are all Poisson point processes, then this function performs an Analysis of Deviance of the fitted models. The output shows the deviance differences (i.e. 2 times log likelihood ratio), the difference in degrees of freedom, and (if test="Chi") the two-sided p-values for the chi-squared tests. Their interpretation is very similar to that in anova.glm.

If some of the fitted models are not Poisson point processes, then the deviance difference is replaced by the adjusted composite likelihood ratio (Pace et al, 2011; Baddeley et al, 2014).

References

Ang, Q.W. (2010) Statistical methodology for events on a network. Master's thesis, School of Mathematics and Statistics, University of Western Australia. Ang, Q.W., Baddeley, A. and Nair, G. (2012) Geometrically corrected second-order analysis of events on a linear network, with applications to ecology and criminology. Scandinavian Journal of Statistics 39, 591--617.

Baddeley, A., Turner, R. and Rubak, E. (2015) Adjusted composite likelihood ratio test for Gibbs point processes. Journal of Statistical Computation and Simulation 86 (5) 922--941. DOI: 10.1080/00949655.2015.1044530.

McSwiggan, G., Nair, M.G. and Baddeley, A. (2012) Fitting Poisson point process models to events on a linear network. Manuscript in preparation.

Pace, L., Salvan, A. and Sartori, N. (2011) Adjusting composite likelihood ratio statistics. Statistica Sinica 21, 129--148.

See Also

lppm

Examples

 X <- runiflpp(10, simplenet)
 mod0 <- lppm(X ~1)
 modx <- lppm(X ~x)
 anova(mod0, modx, test="Chi")