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 hospital 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!