Fantastic paper describes the bias that may arise *from* #regularisation in a multi level model.

https://www.cambridge.org/core/journals/political-analysis/article/understanding-choosing-and-unifying-multilevel-and-fixed-effect-approaches/8101D49CFD3B129F5753FC878F416980

Simple correction the authors propose only works if there is *no* treatment-confounder feedback(see: https://go-bayes.github.io/b-causal/posts/confounder-treatment-feedback/conf-out-feedback.html)

#causalinference #statsdon