On Wed, 16 Jun 2010, Michael Haenlein wrote:
Dear all,
I'm trying to estimate Moran's I using the moran.test function Below
please find the summary statistics for my network and key variable. In
doing so, I'm facing the issue that my estimation results in the
following error message:
Warning message: In moran.test(x, Network_): Out-of-range p-value:
reconsider test arguments
The results are as follows:
Moran's I test under randomisation
data: x
weights: Network
Moran I statistic standard deviate = NA, p-value = NA
alternative hypothesis: greater
sample estimates:
Moran I statistic Expectation Variance
-Inf -0.0002926544 NA
Could anyone please tell me what this error message means?
Well, Moran's I is -Inf, and the analytical variance is NA, so something
is not right. The problem could lie in x, Network, or the lag of x (when
x and Network are OK but their combination is unhappy). Can you run
moran.test() under debug() and check which values lead the value of I to
go to -Inf? Is this what is going on:
data(columbus)
set.seed(1)
x <- log(rpois(n=49, 2))
x
moran.test(x, nb2listw(col.gal.nb))
where the current spdep release fails reporting:
Error in lag.listw(listw, z, zero.policy = zero.policy, NAOK = NAOK) :
Variable contains non-finite values
which was a fix introduced four weeks ago, changed to a test on |Inf| from
a test on NA:
https://r-forge.r-project.org/scm/viewvc.php/pkg/src/lagw.c?root=spdep&r1=244&r2=282
If you update spdep, you'll pick up the improvement (made thanks to a bug
report by Matias Mayor Fernandez), and if this is the case, the problem is
in the x.
Hope this helps,
Roger
Is there a problem with my network and/ or with my key variable?
Thanks very much for letting me know,
Michael
Characteristics of weights list object:
Neighbour list object:
Number of regions: 3418
Number of nonzero links: 6442
Percentage nonzero weights: 0.05514125
Average number of links: 1.884728
Non-symmetric neighbours list
Weights style: NA
Weights constants summary:
n nn S0 S1 S2
NA 3418 11682724 0 NA NA
summary(x)
Min. 1st Qu. Median Mean 3rd Qu. Max.
1082 1543 2119 2250 2886 3965
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--
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: roger.biv...@nhh.no
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