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Compute Local Moran using Matrix Algebra

2 messages · riaarinda, Roger Bivand

Original
riaarinda
# 
I am currently trying to compute local moran's (LISA) using matrix algebra. I
have already get the Ii and E(Ii) values (the result is correctly the same
with Geoda's), but now still confused about getting the Var.Ii, Z.Ii, and
Pr(z > 0). I am still confused about how to get b2 when I try to compute
V(Ii).
Anyone can help telling me how to compute them (Var.Ii, Z.Ii, and Pr(z >
0)), please.
Thank you

The code that I've been using :

library(spdep)
jateng.shp <-
readShapePoly('C:/Users/Toshiba/Documents/DATATIM/3/jateng.shp')
jateng.gal <- read.gal('C:/Users/Toshiba/Documents/DATATIM/3/jateng.gal')
jateng.nb <- nb2listw(jateng.gal)
v1 <- jateng.shp$RCAP107
obs <- NROW(v1)
obs1 <- obs-1
obs2 <- obs-2
ll <- (obs-1)/obs
v1z <- v1-mean(v1)
new_sd_1 <- sd(v1)*ll
a <- v1z/new_sd_1
v1zsdv1 <- v1z/sd(v1)
b <- lag.listw(jateng.nb, v1zsdv1)
unilocmor <- a*b ###### Ii values
wadah <- c(1:obs)
for(i in 1:obs){wadah[i] <- sum(jateng.mat[i,])}
Wi <- wadah
EIi <- Wi/(obs-1) ###### EIi values



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Roger Bivand
#
On Mon, 2 Jul 2012, riaarinda wrote:

            

      
      
      
    

        
Have you looked at the code of the localmoran() function? There you see:

 	b2 <- (sum(z^4, na.rm=NAOK)/n)/(s2^2)

as a (sort of) measure of kurtosis.

Roger