1. The problem statement, all variables and given/known data I know that for both method are used to test the 2 group sample for a non-normally distributed population .... But , i am not sure the difference between them . Can someone explain the difference between them ? When to use sign test and wilcoxon signed rank test ? 2. Relevant equations 3. The attempt at a solution Sorry , i am not sure whether i am posted in the correct section or not .