I have a sample of size 30, being studied for effect of a surgical procedure on certain substance concentration in blood,
In other words, for comparing a measurement change before and after a procedure in a sample of size 30, which test should I use? Wilcoxon signed-rank test or paired t-test?
Best Answer
The Wilcoxon signed rank test is appropriate because there is no reason to believe that the data are even approximately normally distributed and the sample size is only 30.