Nested Hierarchical Model

Hi,

I am a pymc3 newbie and need some guidance to handle nested hierarchical data. I am trying to port a BRMS model from R which has the following lme4 formula

y ~ x1 + x2 + x3 + (1 | x4/x5) -

where the (1 | x4/x5) notation means that the intercept can vary between x4 and also for all the x5 contained within x4. For a more detailed explanation of this notation please refer to pg.7 https://cran.r-project.org/web/packages/lme4/vignettes/lmer.pdf

To take a simple example, let’s consider the radon dataset (https://docs.pymc.io/notebooks/multilevel_modeling.html) where instead of simply focusing on the Minnesota state, we develop a model for all states and then handle counties within those states with a suitable hierarchical formulation.

How to define hyperpriors for such models?

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No very familiar with this (1 | x4/x5) notation, but if you are using brms you can export the Stan code, and usually mapping the Stan code to the PyMC3 code should be straightforward