[R-sig-Geo] R-sig-Geo Digest, Vol 97, Issue 1

[marcelino.delacruz at upm.es]

Lacking more detail on the proposed objectives of this research, I would
suggest Syrjala's test (in the ecespa package) for the difference
between the spatial distributions of two populations.It consists of  a
two-sample Cramer-von Mises (or Kolmogorov-Smirnov)type test for a
difference between the spatial distributions of two populations,
although it focus more on the difference of spatial distributions than
on the differences in abundance between the two ppopulations.

HTH,

Marcelino



Con fecha 1/9/2011, "Mathieu Rajerison" <mathieu.rajerison at gmail.com>
escribió:

>These statistical tests will only give you an idea on how these two matrixes
>differ but they do not take into account connectivity between cells, and
>dates of samples. And it seems that the difference interests you.
>
>Another test you could use is testing for spatial autocorrelation on using
>spdep package, after having established a list of neighbours for each cell
>with cell2nb.
>The test for sp. autocorrelation can either be global either local.
>
>It seems that you have some space time data. Maybe you should have a look at
>spacetime package, also?
>
>I'm just beginning in spatial statistics. Someone will tell me if I'm wrong.
>
>hth,
>
>Mathieu
>
>2011/9/1 Mathieu Rajerison <mathieu.rajerison at gmail.com>
>
>> Giulia,
>>
>>
>> You may look at Pearson, Student or Kolmogorov Smirnov test
>> cor.test, t.test, and ks.test
>> after having coerced your matrixes into vectors
>>
>> Maybe someone has another idea or thinks my advice is not right?
>>
>> hth
>>
>> Mathieu
>>
>> 2011/9/1 Conchedda, Giulia (AGAL) <Giulia.Conchedda at fao.org>
>>
>> Hi to All,
>>>
>>> My question concerns the best practice to compare cell-by-cell two grids
>>> that are representing the same phenomenon (distribution of rural poor). The
>>> grids have the same spatial extent and cell size and I would like to
>>> quantify and provide statistics on how pixel values in the two grids differ.
>>> I first subtracted one from the other and in this way I can already say and
>>> spot where differences are more frequent. What is the best statistics to
>>> quantify this difference?
>>>
>>> Thanks for advising,
>>>
>>> Giulia
>>>
>>> _______________________________________________
>>> R-sig-Geo mailing list
>>> R-sig-Geo at r-project.org
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>
>>
>>
>
>	[[alternative HTML version deleted]]
>
>_______________________________________________
>R-sig-Geo mailing list
>R-sig-Geo at r-project.org
>https://stat.ethz.ch/mailman/listinfo/r-sig-geo