# [R] Problem with Kruskal–Wallis test

Michael Dewey li@t@ @ending from dewey@myzen@co@uk
Sun Dec 23 12:51:07 CET 2018

```I think you need to talk to someone who uses your sort of geographic
data to find out what an appropriate metric for comparing your variables
is. Only then will you know what might be a suitable way forward.

Michael

On 22/12/2018 17:27, Giuseppe Cillis wrote:
> Dear Michael,
> So, I'm not an expert in R and statistics, how can I create this
> interval of confidence of groups?
> Thanks
> Gc
>
> Il giorno sab 22 dic 2018, 13:34 Michael Dewey <lists using dewey.myzen.co.uk
> <mailto:lists using dewey.myzen.co.uk>> ha scritto:
>
>     Dear Giuseppe
>
>     If I understand you correctly you have a very large sample size so
>     it is
>     not surprising that you get very small p-values. Eevn a scientifically
>     uninteresting difference can become statistically significant with
>     large
>     samples. You probably need to define a metric for meaningful
>     differences
>     between groups and calculate a confidence interval for it.
>
>     Michael
>
>     On 21/12/2018 15:37, Giuseppe Cillis wrote:
>      > Dear all,
>      > I am a beginner with R (and also with the statistics) for which I
>     hope to
>      > be clear.
>      > I should do this non-parametric test on data I extracted from maps.
>      > In practice I have a column that represents the landscape
>     Dynamics of a
>      > certain time period (there are 3 dynamics, each of them marked by the
>      > number 1, 2 or 3) and the other column with the values of a
>     topographic
>      > variable (for example the slope) . In all, there are more than
>     90,000 pairs
>      > of values.
>      > Going to do the test in R, for all the dynamics and for all the
>     variables,
>      > I get out of the values of chi-square elevated (even in the order of
>      > thousands) and a p-value always <2.2e-16 .... why? Where can the
>     error be? in
>      > the script or in the test approach?
>      >
>      >       [[alternative HTML version deleted]]
>      >
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>      >
>
>     --
>     Michael
>     http://www.dewey.myzen.co.uk/home.html
>

--
Michael
http://www.dewey.myzen.co.uk/home.html

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