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Need help with Wilcoxon rank-sum test problem!


New member
Feb 25, 2012
Hi guys,

Can anybody help with regards to this question?

Suppose we want to compare the length of hospital stay for patients with same diagnosis at two different hospitals.

First hospital: 5,8,10,13,21,26,29,32,33,44,60
Second hospital: 10,27,35,44,60,68,73,76,86,87,96,125,238

Question1: why might t-test not be very useful in this case? Book said, data is very skewed, but how I can find that myself.

Qestion 2:
Carry out non-parametric procedure for testing the length of stay are comparable in the two hospitals.

The question is answered in the back of the book and I did calculate it by software, but I would like to know how to do it manually, I tried to apply Wilcoxon sum test formula but failed to get the same numbers.
The answers: use Wilcoxon rank-sum test(large-sample test), R1=83.5, T=3.10 , p=.002
Thanks for your help!