[R] correlog function in pgirmess package

[Pascal Oettli]

Hello,

I might be wrong, but I think it is in degree. Let's consider the
length of a degree of longitude at 38N in kilometers: ~88 km

Thus, 40d * 88km = 3520km

Hope this helps,
Pascal


On 5 February 2014 00:43, Alicia <alicia.dalongeville at cirad.fr> wrote:
> Dear R-help,
>
> I used the correlog function of pgirmess package to create a spatial
> correlogram for Moran's I.
> The function gives Moran's coefficient with a p value for each distance
> class. My question is what is the unit for the distance classes?
> Here is the outcome of the function:
>
> Moran I statistic
>       dist.class          coef    p.value    n
>  [1,]   1.283804 -0.0127393244 0.62182018 3288
>  [2,]   3.851412 -0.0070005170 0.53767024 5642
>  [3,]   6.419020 -0.0020360457 0.41371395 6546
>  [4,]   8.986627  0.0173943620 0.07212314 5814
>  [5,]  11.554235 -0.0225794695 0.84271228 4918
>  [6,]  14.121842 -0.0050324772 0.49452160 3372
>  [7,]  16.689450 -0.0007194256 0.42712852 2232
>  [8,]  19.257058 -0.0162570231 0.60272799 1242
>  [9,]  21.824665 -0.0330641732 0.74239660 1208
> [10,]  24.392273  0.0602675483 0.09440368  508
> [11,]  26.959881 -0.0007420201 0.43708138  270
> [12,]  29.527488  0.0765320993 0.10876925  190
> [13,]  32.095096 -0.0046161786 0.44659399  142
> [14,]  34.662703 -0.0797066199 0.61910376   58
> [15,]  37.230311 -0.7840212074 0.99986700   28
> [16,]  39.797919 -0.7770962373 0.99839965   18
>
> I first thought the distance unit was kilometers but the dist.class are only
> going until 40 and my data are taken from all around the Mediterranean sea
> (about 3700km long) so it cannot be right.
>
> In the correlog help it is said that "Distances are in the same unit as the
> spatial coordinates" but I don't get what that means. I gave spatial
> coordinates in decimal degree.
>
> It must be very simple but I was not able to find the answer anywhere.
>
> Thanks for your help,
> Cheers,
>
> Alicia
>
>
>
> --
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>
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-- 
Pascal Oettli
Project Scientist
JAMSTEC
Yokohama, Japan