# Levels within levels

I am working on some professor rating data. I would like to model the data in a multilevel fashion as professors are nested within departments, and departments are nested within the school. This is similar to the 8 schools example, except now there is an additional level. From the model, I would like to infer the random effect of the department and the random effect of each instructor.

I’m new to brms and a bit confused on how to specify this relationship. One of the vignettes notes I can use

`Average_Rating|se(Rating_Se)~ 1 + (1|Professor_Name/Department)`

Does this specify the relationship I’m trying to estimate correctly?

• Operating System: mac os 10.14.4
• brms Version: 2.7.0

I think the grouping variables should be the other way round so that you end up with department and professor within department. but you should verify this is correct. I always get confused as well… :-)

So the grouping goes the other way around?

`outcome ~ 1 + (1|larger_level/level_within_level)`

I think so but you need to verify this.

OK, will do. Thanks!

`(1|A/B)` can also be written as `(1|A) + (1|A:B)`. Conversely,
`(1|B/A)` is equal to `(1|B) + (1|B:A)`

so if you want (random effects) coefficients for each of your larger levels,
`outcome ~ 1 + (1|larger_level/level_within_level)` it is.

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