I have the samples from two mouse strains in both genders.
The design formulas I have are:
formula 1: ~ strain # test the effect of different strains formula 2: ~ strain + gender # test for the effect of gender controlling for the effect of different mouse strains formula 3: ~ strain + gender + stain:gender # test which genes the effect of gender is different across different mouse strains
Here the problem is, I'm not sure if gender has an effect on the gene expression.
So I want to test if it's meaningful by adding gender and the interaction terms in the design formula, as the results vary a lot with different formulas.
I'm not familiar with statistics. Could anyone give me a hint on how to test it?
Thanks a lot!