prab.sarestimate: Estimates SAR model from log-abundance matrix of prab-object.

Description

This is either an interface for the function errorsarlm for abundance data stored in an object of class prab implemented for use in abundtest, or, in case that spatial information should be ignored, it estimates a two-way additive unreplicated linear model for log-abundances on factors species and region.

Usage

prab.sarestimate(abmat, prab01=NULL,sarmethod="eigen",
                             weightstyle="C",
                             quiet=TRUE, sar=TRUE,
                             add.lmobject=TRUE)

Value

A list with the following components:

sar: see above.
intercept: numeric. Estimator of the intercept.
sigma: numeric. Estimator of error standard deviation.
regeffects: numeric vector. Estimator for region effects.
speceffects: numeric vector. Estimator for species effects.
lamda: numeric. Governs the degree of spatial autocorrelation. See errorsarlm.
size: integer. Length of neighborhood list generated by nb2listw used by errorsarlm.
nbweight: numeric. Average weight of neighbors.
lmobject: if add.lmobject=TRUE, output object of either lm or errorsarlm.

Arguments

abmat: object of class prab.
prab01: presence-absence matrix of same dimensions than the abundance matrix of prabobj. This specifies the presences and absences on which the presence/absence step of abundance-based tests is based (see details). If NULL (which is usually the only reasonable choice), prab01 is computed in order to indicate the nonzeroes of prabobj$prab.
sarmethod: this is passed on as parameter method to errorsarlm and documented there. We don't have experience with any other choice than "eigen".
weightstyle: can take values "W", "B", "C", "U", and "S" though tests suggest that "C" should be chosen. See nb2listw.
quiet: this is passed on as parameter quiet to errorsarlm and documented there.
sar: logical. If TRUE, a simultaneous autoregression model is fitted by calling errorsarlm. If FALSE, a two-way additive unreplicated linear model for log-abundances on factors species and region is computed by lm, ignoring the spatial arrangement of the regions.
add.lmobject: logical. If TRUE, the whole output object of errorsarlm (or lm) is given out.

Author

Christian Hennig christian.hennig@unibo.it https://www.unibo.it/sitoweb/christian.hennig/en

Examples

Run this code

  options(digits=4)
  data(siskiyou)
  x <- prabinit(prabmatrix=siskiyou, neighborhood=siskiyou.nb,
             distance="none")
#  Not run; this needs package spdep 
#  prab.sarestimate(x)
  prab.sarestimate(x, sar=FALSE)