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
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Michael
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