I’ve been successful in generating a simply y~x linear model with stan_glm. Now, I’d like to set my priors based on the knowledge I have regarding the data.

For example, the intercept will probably lie between 1.2 & 1.6, but NEVER <= 1. Likewise, the slope will be around -1, but NEVER >= 0.

I tried it by setting prior_intercept to normal(1.5, 0.5), but that ended in the model having equal amounts of positive as negative slopes. Maybe I’m just not understanding the normal() function.