# [R] Problem with Kruskal–Wallis test

Giuseppe Cillis giucilli@ @ending from gm@il@com
Sat Dec 22 18:27:41 CET 2018

```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> 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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> > and provide commented, minimal, self-contained, reproducible code.
> >
>
> --
> Michael
> http://www.dewey.myzen.co.uk/home.html
>

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