aple.plot {spdep}R Documentation

Approximate profile-likelihood estimator (APLE) scatterplot

Description

A scatterplot decomposition of the approximate profile-likelihood estimator, and a local APLE based on the list of vectors returned by the scatterplot function.

Usage

aple.plot(x, listw, do.plot=TRUE, ...)
localAple(x, listw)

Arguments

x a zero-mean detrended continuous variable
listw a listw object from for example nb2listw
do.plot default TRUE: should a scatterplot be drawn
... other arguments to be passed to plot

Details

The function solves a secondary eigenproblem of size n internally, so constructing the values for the scatterplot is quite compute and memory intensive, and is not suitable for very large n.

Value

aple.plot returns list with components:

X A vector as described in Li et al. (2007), p. 366.
Y A vector as described in Li et al. (2007), p. 367.


localAple returns a vector of local APLE values.

Author(s)

Roger Bivand Roger.Bivand@nhh.no

References

Li, H, Calder, C. A. and Cressie N. A. C. (2007) Beyond Moran's I: testing for spatial dependence based on the spatial autoregressive model. Geographical Analysis 39, pp. 357-375.

See Also

aple

Examples

example(aple)
plt_out <- aple.plot(scale(wheat$yield_detrend, scale=FALSE),
 nb2listw(nbr12, style="W"), cex=0.6)
crossprod(plt_out$Y, plt_out$X)/crossprod(plt_out$X)
lm_obj <- lm(Y ~ X, plt_out)
abline(lm_obj)
abline(v=0, h=0, lty=2)
zz <- summary(influence.measures(lm_obj))
infl <- as.integer(rownames(zz))
points(plt_out$X[infl], plt_out$Y[infl], pch=3, cex=0.6, col="red")
wheat$localAple <- localAple(scale(wheat$yield_detrend, scale=FALSE),
 nb2listw(nbr12, style="W"))
mean(wheat$localAple)
hist(wheat$localAple)
spl <- list("sp.text", coordinates(wheat)[infl,], rep("*", length(infl)))
spplot(wheat, "localAple", sp.layout=spl)

[Package spdep version 0.4-34 Index]