# [R] Problem with Kruskal–Wallis test

Bert Gunter bgunter@4567 @ending from gm@il@com
Tue Dec 25 16:22:10 CET 2018

```"So, I'm not an expert in R and statistics" ....

So you need to seek local help from someone who is. Statistics is usually
off-topic for this list -- it is about R programming primarily. And online
is probably not a good venue for the sort of discussion you need anyway.

Cheers,
Bert

Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )

On Tue, Dec 25, 2018 at 5:37 AM Giuseppe Cillis <giucillis using gmail.com> 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>
> 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?
> > > Thanks in advance
> > >
> > >       [[alternative HTML version deleted]]
> > >
> > > ______________________________________________
> > > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > > https://stat.ethz.ch/mailman/listinfo/r-help
> > > PLEASE do read the posting guide
> > http://www.R-project.org/posting-guide.html
> > > and provide commented, minimal, self-contained, reproducible code.
> > >
> >
> > --
> > Michael
> > http://www.dewey.myzen.co.uk/home.html
> >
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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