[R] significance test interquartile ranges

Greg Snow 538280 at gmail.com
Fri Jul 13 22:37:39 CEST 2012

A permutation test may be appropriate:

1. compute the ratio of the 2 IQR values (or other comparison of interest)
2. combine the data from the 2 samples into 1 pool, then randomly
split into 2 groups (matching sample sizes of original) and compute
the ratio of the IQR values for the 2 new samples.
3. repeat #2 a bunch of times (like for a total of 999 random splits)
and combine with the original value.
4. (optional, but strongly suggested) plot a histogram of all the
ratios and place a reference line of the original ratio on the plot.
5. calculate the proportion of ratios that are as extreme or more
extreme than the original, this is the (approximate) p-value.

On Fri, Jul 13, 2012 at 5:32 AM, Schaber, Jörg
<joerg.schaber at med.ovgu.de> wrote:
> Hi,
> I have two non-normal distributions and use interquartile ranges as a dispersion measure.
> Now I am looking for a test, which tests whether the interquartile ranges from the two distributions are significantly different.
> Any idea?
> Thanks,
> joerg
>         [[alternative HTML version deleted]]
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Gregory (Greg) L. Snow Ph.D.
538280 at gmail.com

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