Thanks a lot! I think this explains the difference between two contradicting results: The ranked values of length of stay within each group are very similar to each other hence the insignificant Wilcoxon Rank Sum Test (i.e. Wilcoxon Mann-Whitney) results yet the medians are different enough to have a statistically significant different Median Two-Sample Test results. This shows that one should be very careful interpreting the test results! Though I still wonder what's the use of "Median Two-Sample" test? By the way I said above that I would post here SAS's response and here it is: "Hi Recep, You can find the formulas in the documentation here, if you would like to review them. Most people use the Wilcoxon rank sum test to compare the medians of two groups of data, however you may need to consult with a statistician regarding your particular analysis and input data. Sincerely, XXX SAS Technical Support "
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