spdep (version 1.2-7)

moran_bv: Compute the Global Bivariate Moran's I

Description

Given two continuous numeric variables, calculate the bivariate Moran's I. See details for more.

Usage

moran_bv(x, y, listw, nsim = 499, scale = TRUE)

Value

An object of class "boot", with the observed statistic in component t0.

Arguments

x

a numeric vector of same length as y.

y

a numeric vector of same length as x.

listw

a listw object for example as created by nb2listw().

nsim

the number of simulations to run.

scale

default TRUE.

Author

Josiah Parry

Details

The Global Bivariate Moran is defined as

\( I_B = \frac{\Sigma_i(\Sigma_j{w_{ij}y_j\times x_i})}{\Sigma_i{x_i^2}} \)

It is important to note that this is a measure of autocorrelation of X with the spatial lag of Y. As such, the resultant measure may overestimate the amount of spatial autocorrelation which may be a product of the inherent correlation of X and Y.

References

Wartenberg, D. (1985), Multivariate Spatial Correlation: A Method for Exploratory Geographical Analysis. Geographical Analysis, 17: 263-283. tools:::Rd_expr_doi("10.1111/j.1538-4632.1985.tb00849.x")

Examples

data(boston, package = "spData")
x <- boston.c$CRIM
y <- boston.c$NOX
listw <- nb2listw(boston.soi)
set.seed(1)
res_xy <- moran_bv(x, y, listw, nsim=499)
res_xy$t0
plot(res_xy)
set.seed(1)
lee_xy <- lee.mc(x, y, listw, nsim=499, return_boot=TRUE)
lee_xy$t0
plot(lee_xy)
set.seed(1)
res_yx <- moran_bv(y, x, listw, nsim=499)
res_yx$t0
plot(res_yx)
set.seed(1)
lee_yx <- lee.mc(y, x, listw, nsim=499, return_boot=TRUE)
lee_yx$t0
plot(lee_yx)