How are the p-values calculated from the S test statistic in the Wilcoxon signed rank test in JMP

[SheilaR]

Hi, I'm trying to make sure I understand how the S test-statistic and corresponding p-values are being calculated in the Wilcoxon Signed Rank test in JMPs Matched Pairs Platform.  For example, if I compare two columns of data using the Matched pairs analysis in JMP and selected the Wilcoxon Signed Rank option, I see a Test Statistic S= 15.5 and a Prob>|S|= 0.2832.  I'm wondering what distribution of S (or other strategy) is JMP is using to calculate the p-value?

I can see from the basic analysis JMP pdf that W is computed as equal to 1/2 (sum of signed ranks).  I'm assuming that W is equivalent to S in this case.  Is that correct?

And again, I'm not sure how the p-value is calculated here.

I'm confused as to how the JMP output compares to, for example, calculating a test-statistic and determining whether it is a less than a given value (as a function of the sample size) in order to determine whether to reject the null hypothesis that the medians are the same.

Thank you in advance for any help! I really appreciate it!

[Reeza]

JMP support can be obtained on this forum:

https://community.jmp.com/community/discussions

[SheilaR]

Thank you!