Hello, I'm working in R, and trying to understand the decision, post-matching, between using model = 'linear' and model = 'linear-RE' in the specification of att(), like this: ## data(LL) todrop <- c("treated","re78") # cem match: automatic bin choice mat <- cem(treatment="treated", data=LL, drop="re78") mat # models att(mat, re78 ~ treated, data=LL, model = 'linear') att(mat, re78 ~ treated, data=LL, model = 'linear-RE') The SATT is a bit different across models, but what's really striking is how relatively tiny the standard errors are when model = 'linear-RE'. Is there something I could read on the motivation behind 'linear-RE', contexts where it might be appropriate, etc.? Thank you, Juan Tellez -- Juan Fernando Tellez http://juanftellez.com Department of Political Science Duke University