We could easily make a two-way anova to test whether there is an interaction between two independent variables, but it is advisable to do a bayesian inference when the p value is not so straightforward (such as a marginal p value). I refered to a book "Bayesian Modeling Using WinBUGS" to achieve this in WinBUGS software. The model is as following(2×2 within group design,30 samples):
model{
for (a in 1:LA){
for (b in 1:LB){
for (k in 1:K){
y[a,b,k] ~ dnorm( mu[a,b,k], tau)
mu[a,b,k]