David,

>
>  I am sure I am opening myself up to looking stupid,
>>
>
> Or exposing a failure to read the help page.


Well no, and of course I did read the help pages as well as several
introductions on Wilcoxon before posting,  but as I said in my other post it
is generally not at all clear, the distinction between difference between
medians and median differences.

I didn't find the help page all that enlightening, given that I came to them
with a firm misconception about medians< and the dummy data sets I created
to try and work out what might be going on, plus data sets I pulled from
Wilcoxon tutorials gave  differences in medians that matched the Wilcoxon
median differences.

Now that I realise that the Wilcoxon gives median differences, and how they
are calculated, it all makes more sense.

I realise the data are highly skewed, but what started out as a quick look
to see what a Wilcoxon looked like with this data, became an all morning
search through text books and google, together with experiments in R, to try
and work out why I was getting this discrepancy in locations.

I now know why.

Thanks,

Graham

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