[R-sig-Geo] inconsistent results from moran.test()

[Roger Bivand]

On Fri, 8 Mar 2019, Jay Wang wrote:

> Hello,
>
> Having my own spatial weight matrix, I converted it to a listw format and
> calculated the Moran index. The codes are listed below:
>
> Wod_lw<-mat2listw(Wod)
> moran.test(mydata$Ties_processed,Wod_lw, randomisation=TRUE)

Here, Wod_lw has an unknown style, "M" for matrix.

>
> However, after I generated a gal file, imported it, converted it back to a
> listw file, and re-calculated the Moran index with the following codes, the
> results became totally different (0.1624 vs. 0.1942):
> write.nb.gal(Wod_lw$neighbours,"Wod.gal")

This only writes the neighbours (read the help page), not the weights.

> Wod.gal.nb <- read.gal(file="Wod.gal")
> Wod_lw2<-nb2listw(Wod.gal.nb)

The default style in nb2listw() is "W", row standardised.

What does:

all.equal(Wod_lw$weights, Wod_lw2$weights, check.attributes=FALSE)

say? And:

all.equal(Wod_lw$neighbours, Wod_lw2$neighbours, check.attributes=FALSE)

> moran.test(mydata$Ties_processed,Wod_lw, randomisation=TRUE)
> moran.test(mydata$Ties_processed,Wod_lw2, randomisation=TRUE)
>
> I don't know where the problem is. I would appreciate if anyone can help me
> with this. Thank you

Do read the help pages, you'll find they explain these things.

Roger

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-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; e-mail: Roger.Bivand using nhh.no
https://orcid.org/0000-0003-2392-6140
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