[R] Comparing two pairs of non-normal datasets in R?
Peter Sebastian Masny
ps-list at masny.dk
Tue Jun 8 21:14:28 CEST 2004
On Tuesday 08 June 2004 10:43 am, you wrote:
> If I understand you correctly, you have two set of ***paired***
> data, one set from the A population, and one from the C population.
>
> Form the pairwise differences:
>
> A.diff <- A1 - A2
> C.diff <- C1 - C2
Alas, they are not paired. A1 and A2 are samples from the same population,
but of different members. Also, the number of measurements is different for
each dataset.
> Boxplots and histograms of A.diff and C.diff will tell you
> (much more than a test ever would) what's ***really*** going on.
The boxplots I have clearly show the difference, but I need a p value to go
with it.
Here are the boxplots if that helps:
http://www.ps.masny.dk/guests/misc/A1.png
http://www.ps.masny.dk/guests/misc/A2.png
http://www.ps.masny.dk/guests/misc/C1.png
http://www.ps.masny.dk/guests/misc/C2.png
> P.S. BTW --- you say that your data are continuous, but that their
> distributions are ``more like a Poisson''. The Poisson distribution
> is DISCRETE!!!
Hence the "like". The data is indeed continuous, but a distribution graph
increases towards one extreme...
Visually, the results are convincing, but I really need a test of
significance.
Thank you very much for the help,
Peter
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