Do I need to transform my response variable to fit a lognormal GLM in brms?

Interfaces brms
,
2

If you want to run a log-normal GLM with brms (or another package for that matter), you can either:

  1. log-transform your data and run a regular LM (link function = identity), or
  2. Directly analyse the data with a GLM with log as link function and a log-normal likelihood (the “family” in R lingo).

Both methods should yield the same parameter estimates (provided there aren’t subtle aspects you did not describe, like clustering of data, for which a regular LM would not be appropriate).

2 Likes