Hi!

Is it possible to test for differential expression among interactions and contrasts in Ballgown? I have a treatment group (drug/control) and sex (m/f). I would like to know the effect of each interaction drug*male, drug*female, control*male, control*female. 

Thanks!

Have you read the ballgown vignette? You can pass in two design matrices, one in which you have dropped the coefficients you want to test, so it should be straightforward to test for an interaction.