

Dear
R-users,


I was
wondering if someone could give me some advices on the following problem. 

I tried to
apply moran’s test to a small dataset and couldn’t succeed, here is the error
message:

 

mor <- moran.test(x, res2)

 

Avis dans
moran.test(x, res2) :

  Out-of-range p-value: reconsider test arguments

 

mor

 

 
Moran's I test under randomization

data:  x  

weights: res2  

 Moran I statistic standard deviate = NaN, p-value = NA

alternative hypothesis: greater 

sample estimates:

Moran I statistic       Expectation          Variance 

     
-0.04166667       -0.04166667        0.00000000

 

 It seems that I have a problem computing the
standard deviation, variance and/or p-value.


As a brief
overview of what are x and res2: I have a square sample plot on the field divided
into 5 lines / 5 columns and one value per “sub-plot”, so a dataframe of 25
values (25 cells and 1 value per cell…). 
The parameter x is a numeric vector containing those 25 values:


str(x)

num [1:25]
22920 19546 16170 21387 9499 ...


To obtain
my spatial weight matrix, I used 2 columns (X & Y) representing the
coordinates of the center of each sub-plot (20x20m, so 10:10, 10:30, 10:50,
etc.), transformed it into a neighborhood matrix of class “nb” with dnearneigh() function, then into a object of class “listw” with nb2listw() function (with style=”B”).  I end up with “res2” : 



res2

Characteristics of weights list
object:

Neighbour list object:

Number of regions: 25 

Number of nonzero links: 600 

Percentage nonzero weights: 96 

Average number of links: 24 

 

Weights style: B 

Weights constants summary:

  
n  nn  S0  
S1    S2

B 25 625 600 1200 57600

 

Ok so it seems quiet straightforward
to me and I cannot figure out from where my problem is coming !!! any idea ?

with regards





      
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