ME {spdep} | R Documentation

## Moran eigenvector GLM filtering

### Description

The Moran eigenvector filtering function is intended to remove spatial autocorrelation from the residuals of generalised linear models. It uses brute force eigenvector selection to reach a subset of such vectors to be added to the RHS of the GLM model to reduce residual autocorrelation to below the specified alpha value.

### Usage

    ME(formula, data, family = gaussian, weights, offset, listw,
     alpha=0.05, nsim=99, verbose=TRUE, stdev=FALSE)

### Arguments

`formula` | a symbolic description of the model to be fit
`data` | an optional data frame containing the variables in the model
`family` | a description of the error distribution and link function to be used in the model
`weights` | an optional vector of weights to be used in the fitting process
`offset` | this can be used to specify an a priori known component to be included in the linear predictor during fitting
`listw` | a `listw` object created for example by `nb2listw`
`alpha` | used as a stopping rule to choose all eigenvectors up to and including the one with a p-value exceeding alpha
`nsim` | number of permutations for permutation bootstrap for finding p-values
`verbose` | if TRUE report eigenvectors selected
`stdev` | if TRUE, p-value calculated from bootstrap permutation standard deviate using `pnorm` with alternative="greater", if FALSE the Hope-type p-value

### Details

The eigenvectors for inclusion are chosen by calculating the empirical Moran's I values for the initial model plus each of the doubly centred symmetric spatial weights matrix eigenvectors in turn. Then the first eigenvector is chosen as that with the lowest Moran's I value. The procedure is repeated until the lowest remaining Moran's I value has a permutation-based probability value above alpha. The probability value is either Hope-type or based on using the mean and standard deviation of the permutations to calculate ZI based on the stdev argument.

### Value

An object of class `ME_res`:

`selection` | a matrix summarising the selection of eigenvectors for inclusion, with columns: Eigenvector number of selected eigenvector ZI permutation-based standardized deviate of Moran's I if stdev=TRUE pr(ZI) probability value: if stdev=TRUE of the permutation-based standardized deviate, if FALSE the Hope-type probability value, in both cases on-sided The first row is the value at the start of the search
`vectors` | a matrix of the selected eigenvectors in order of selection

### Author(s)

Roger Bivand and Pedro Peres-Neto

### References

Dray S, Legendre P and Peres-Neto PR (2005) Spatial modeling: a comprehensive framework for principle coordinate analysis of neigbbor matrices (PCNM), Ecological Modelling; Griffith DA and Peres-Neto PR (2006) Spatial modeling in ecology: the flexibility of eigenfunction spatial analyses.

### See Also

`SpatialFiltering`, `glm`

### Examples

    ## Not run:
    example(columbus)
    lmbase <- lm(CRIME ~ INC + HOVAL, data=columbus)
    lagcol <- SpatialFiltering(CRIME ~ 1, ~ INC + HOVAL, data=columbus,
     nb=col.gal.nb, style="W", alpha=0.1, verbose=TRUE)
    lagcol
    lmlag <- lm(CRIME ~ INC + HOVAL + fitted(lagcol), data=columbus)
    anova(lmlag)
    anova(lmbase, lmlag)
    set.seed(123)
    lagcol1 <- ME(CRIME ~ INC + HOVAL, data=columbus, family="gaussian",
     listw=nb2listw(col.gal.nb), alpha=0.1, verbose=TRUE)
    lagcol1
    lmlag1 <- lm(CRIME ~ INC + HOVAL + fitted(lagcol1), data=columbus)
    anova(lmlag1)
    anova(lmbase, lmlag1)
    set.seed(123)
    lagcol2 <- ME(CRIME ~ INC + HOVAL, data=columbus, family="gaussian",
     listw=nb2listw(col.gal.nb), alpha=0.1, stdev=TRUE, verbose=TRUE)
    lagcol2
    lmlag2 <- lm(CRIME ~ INC + HOVAL + fitted(lagcol2), data=columbus)
    anova(lmlag2)
    anova(lmbase, lmlag2)
    example(nc.sids)
    glmbase <- glm(SID74 ~ 1, data=nc.sids, offset=log(BIR74),
     family="poisson")
    set.seed(123)
    MEpois1 <- ME(SID74 ~ 1, data=nc.sids, offset=log(BIR74),
     family="poisson", listw=nb2listw(ncCR85_nb), alpha=0.2, verbose=TRUE)
    MEpois1
    glmME <- glm(SID74 ~ 1 + fitted(MEpois1), data=nc.sids, offset=log(BIR74),
     family="poisson")
    anova(glmME, test="Chisq")
    anova(glmbase, glmME, test="Chisq")
    data(hopkins)
    hopkins_part <- hopkins[21:36,36:21]
    hopkins_part[which(hopkins_part > 0, arr.ind=TRUE)] <- 1
    hopkins.rook.nb <- cell2nb(16, 16, type="rook")
    glmbase <- glm(c(hopkins_part) ~ 1, family="binomial")
    set.seed(123)
    MEbinom1 <- ME(c(hopkins_part) ~ 1, family="binomial",
     listw=nb2listw(hopkins.rook.nb), alpha=0.2, verbose=TRUE)
    glmME <- glm(c(hopkins_part) ~ 1 + fitted(MEbinom1), family="binomial")
    anova(glmME, test="Chisq")
    anova(glmbase, glmME, test="Chisq")
    ## End(Not run)

[Package spdep version 0.4-56 Index]