I am working with biological data. The project is about comparing microbiota composition in different samples who have different type of diet. Here is the experimental design of the project:
1) factor diet -> levels: a) baseline b) white bread(wb) c) barley bread(bb) 2) factor responded (if have high blood glucose) -> levels: a) responders b)non-responders sot it would be: baseline wb bb baseline wb bb |_____________________| |_____________________| Responders non-responders
I have seen big difference between amount of one bacteria in bb-responders and bb-nonResponders. Since the data is not normally districted if I use ttest I will not get any significant value. One suggested me to use Mann Whitney U-test but I am not sure what kind of test I have to use! Could you please help me with that?