moran.bi {bispdep}

Compute Bivariate Moran's Ixy

Description

A simple function to compute bivariate Moran's Ixy, called by moranbi.test and moranbi.mc;

I = \frac{n}{\sum_{i=1}^{n}\sum_{j=1}^{n}w_{ij}} \frac{\sum_{i=1}^{n}\sum_{j=1}^{n}w_{ij}(x_i-\bar{x})(y_j-\bar{y})}{\sum_{i=1}^{n}(x_i - \bar{x})^2}

Usage

moran.bi(varX, varY, listw, zero.policy=NULL, adjust.n = TRUE, NAOK=FALSE)

Arguments

varX

a numeric vector of the same length as the neighbours list in listw with the values of the variable x

varY

a numeric vector of the same length as the neighbours list in listw with the values of the variable y

listw

a listw object created for example by nb2listw

zero.policy

default NULL, use global option value; if TRUE assign zero to the lagged value of zones without neighbours, if FALSE assign NA

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

NAOK

if 'TRUE' then any 'NA' or 'NaN' or 'Inf' values in x are passed on to the foreign function. If 'FALSE', the presence of 'NA' or 'NaN' or 'Inf' values is regarded as an error.

Value

a list of

I

Bivariate Moran's I

Kx

sample kurtosis of the variable X

Ky

sample kurtosis of the variable Y

References

Czaplewski, R.L., Reich, R.M. 1993. Expected value and variance of Moran's bivariate spatial autocorrelation statistic for a permutation test, Research paper RM-309, Fort Collins, CO U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station, p, 13.

See Also

moranbi.test, moranbi.mc

Examples

library(spdep)
data(oldcol)
col.W <- nb2listw(COL.nb, style="W")
crime <- COL.OLD$CRIME
inc <- COL.OLD$INC
str(moran.bi(crime, inc, col.W, zero.policy = TRUE, NAOK=FALSE))
set.seed(123)
is.na(crime) <- sample(1:length(crime), 5)
is.na(inc) <- sample(1:length(inc), 10)
str(moran.bi(crime, inc, col.W, zero.policy = TRUE, NAOK=TRUE))