# ecospat.permut.glm: GLM Permutation Function In ecospat: Spatial Ecology Miscellaneous Methods

 ecospat.permut.glm R Documentation

## GLM Permutation Function

### Description

A permutation function to get p-values on GLM coefficients and deviance.

### Usage

`ecospat.permut.glm (glm.obj, nperm, verbose = FALSE)`

### Arguments

 `glm.obj` Any calibrated GLM or GAM object with a binomial error distribution. `nperm` The number of permutations in the randomization process. `verbose` Boolean indicating whether to print progress output during calculation. Default is FALSE.

### Details

Rows of the response variable are permuted and a new GLM is calibrated as well as deviance, adjusted deviance and coefficients are calculated. These random parameters are compared to the true parameters in order to derive p-values.

### Value

Return p-values that are how the true parameters of the original model deviate from the disribution of the random parameters. A p-value of zero means that the true parameter is completely outside the random distribution.

### Author(s)

Christophe Randin christophe.randin@unibas.ch, Antoine Guisan antoine.guisan@unil.ch and Trevor Hastie

### References

Hastie, T., R. Tibshirani and J. Friedman. 2001. Elements of Statistical Learning; Data Mining, Inference, and Prediction, Springer-Verlag, New York.

Legendre, P. and L. Legendre. 1998. Numerical Ecology, 2nd English edition. Elsevier Science BV, Amsterdam.

### Examples

```

if(require("rms",quietly=TRUE)){
data('ecospat.testData')

# data for Soldanella alpina

# gbm model for Soldanella alpina

glm.Solalp <- glm(Soldanella_alpina ~ pol(ddeg,2) + pol(mind,2) + pol(srad,2) + pol(slp,2)
+ pol(topo,2), data = data.Solalp, family = binomial)

# p-values
ecospat.permut.glm (glm.Solalp, 1000)
}

```

ecospat documentation built on Nov. 10, 2022, 5:55 p.m.