Your questions were similar to mine. I perused the article and hope to read it very carefully later today, but I wondered how often you wouldn't expect unobserv

Your questions were similar to mine. I perused the article and hope to read it very carefully later today, but I wondered how often you wouldn't expect unobserved variables to be playing some role, especially in observational data. It's an interesting paper, but when I think of rigorous evaluation of its ideas I get a little confused. I'm probably missing something though.