How to extract subset of the parameters when using dims?

I have assigned a parameter to have different levels

params = {}
coords = {"health_authority": data["HA"]}
with pm.Model(coords=coords) as model:
    params["β[vol|pop]"] = pm.Normal(
            "β[vol|pop]", mu=0, sigma=10, dims="health_authority"

Plotting using az.plot_trace I see these parameters take on distinct values:

But when I try to isolate one of the health authorities it doesn’t appear to be splitting as I thought.

How do extract the subset of the parameters for a given health authority (e.g. “Interior”)?

Not sure I completely follow the question or the code, but my first recommendation would be to check Working with InferenceData — ArviZ 0.16.1 documentation