what makes a gam factor interaction possible when a simple smooth gam which is true about the sum to zero constraint of the gam factor? gam factor interaction what constraint is used to make smooths fit gam factor interaction if one were to sum the smooth over the values of its covariates, it would equal zero can smooths fit what is the constraint for gam factor interaction with smooths when a smooth is interacted with a factor, a gam factor is? when a smooth is interacted with a factor, this is the case: what condition is used to create an interacted smooth which factor is affected by gam factor interaction? what is the constraint of gam factor interaction what is the constraint on GAM factor interaction when the smooth is interacted with a factor, the sum is equal to zero. how to find the zero value for gam factor when a smooth is interacted with an factor, the smooth would equal zero what is the difference between a sum to zero and a zero factor? which factor does gam factor interaction which is not true for gam factor interaction