# calculate a P value using a permutation test

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noa goldman on 11 Jan 2020
Answered: Jeff Miller on 12 Jan 2020
How can I calculate a P value using a permutation test for these 2 groups?
controlA=[0.22, -0.87, -2.39, -1.79, 0.37, -1.54, 1.28, -0.31, -0.74, 1.72, 0.38, -0.17, -0.62, -1.10, 0.30, 0.15, 2.30, 0.19, -0.50, -0.09];
treatmentA=[-5.13, -2.19, -2.43, -3.83, 0.50, -3.25, 4.32, 1.63, 5.18, -0.43, 7.11, 4.87, -3.10, -5.81, 3.76, 6.31, 2.58, 0.07, 5.76, 3.50];
I know that both samples come from the same distribution.
thanks

Star Strider on 11 Jan 2020
In MATLAB, use the ranksum function.
p =
0.350702223666955
h =
0
stats =
zval: -0.933228071880792
ranksum: 375
So the ‘p’ value indicates that they are not significantly different, and ‘h’ indicates that the null hypothesis is not rejected.

noa goldman on 11 Jan 2020
Thank you very much, but you calculated it using the Wilcoxon test and I have to program it using the permutation test.
Star Strider on 11 Jan 2020
I have never heard of the ’permutation test’. When I did an Interweb search on it, the Wilcoxon rank-sum test came up in several examples. That is the reason I use it here.

Jeff Miller on 12 Jan 2020
This contribution on file exchange looks like it will do what you want.