R: Permutation test for Geary's C statistic

geary.mc {spdep} | R Documentation

## Permutation test for Geary's C statistic

### Description

A permutation test for Geary's C statistic calculated by using nsim random permutations of x for the given spatial weighting scheme, to establish the rank of the observed statistic in relation to the nsim simulated values.

### Usage

    geary.mc(x, listw, nsim, zero.policy=NULL, alternative="greater",
     spChk=NULL, adjust.n=TRUE, return_boot=FALSE)

### Arguments

`x` | a numeric vector the same length as the neighbours list in listw
`listw` | a `listw` object created for example by `nb2listw`
`nsim` | number of permutations
`zero.policy` | default NULL, use global option value; if TRUE assign zero to the lagged value of zones without neighbours, if FALSE assign NA
`alternative` | a character string specifying the alternative hypothesis, must be one of "greater" (default), or "less"; this reversal corresponds to that on `geary.test` described in the section on the output statistic value, based on Cliff and Ord 1973, p. 21 (changed 2011-04-11, thanks to Daniel Garavito).
`spChk` | should the data vector names be checked against the spatial objects for identity integrity, TRUE, or FALSE, default NULL to use `get.spChkOption()`
`adjust.n` | default TRUE, if FALSE the number of observations is not adjusted for no-neighbour observations, if TRUE, the number of observations is adjusted
`return_boot` | return an object of class `boot` from the equivalent permutation bootstrap rather than an object of class `htest`

### Value

A list with class `htest` and `mc.sim` containing the following components:

`statistic` | the value of the observed Geary's C.
`parameter` | the rank of the observed Geary's C.
`p.value` | the pseudo p-value of the test.
`alternative` | a character string describing the alternative hypothesis.
`method` | a character string giving the method used.
`data.name` | a character string giving the name(s) of the data, and the number of simulations.
`res` | nsim simulated values of statistic, final value is observed statistic

### Author(s)

Roger Bivand Roger.Bivand@nhh.no

### References

Cliff, A. D., Ord, J. K. 1981 Spatial processes, Pion, p. 63-5.

### See Also

`geary`, `geary.test`

### Examples

    data(oldcol)
    sim1 <- geary.mc(COL.OLD$CRIME, nb2listw(COL.nb, style="W"),
     nsim=99, alternative="less")
    sim1
    mean(sim1$res)
    var(sim1$res)
    summary(sim1$res)
    colold.lags <- nblag(COL.nb, 3)
    sim2 <- geary.mc(COL.OLD$CRIME, nb2listw(colold.lags[[2]],
     style="W"), nsim=99)
    sim2
    summary(sim2$res)
    sim3 <- geary.mc(COL.OLD$CRIME, nb2listw(colold.lags[[3]],
     style="W"), nsim=99)
    sim3
    summary(sim3$res)

[Package spdep version 0.6-13 Index]