In the GLM Poisson regression example (http://docs.pymc.io/notebooks/GLM-poisson-regression.html?highlight=transform) there is a variable transformation that applies the inverse-link (exp) on the Beta coefficients. Then, the developer comments the effects of the variables. For example he comments “non-zero positive effect of adding alcohol”. Can it be really zero?

Thus, it is not clear why he transform variables to comment the effects: by transforming he can’t event see negative effects (e.g. millions of euro spent in police forces <-> crime counts). Moreover, non of the variables can be zero (event with horseshoe or LASSO). Can you help me understanding the choice?

thx