Into data before it was big. A great man for things that do not yet exist. Contact me if you are working on interesting problems and want to talk to an economist.

Please do not e-mail me with questions unless we drank at least one beer together. I am happy to help, but I won't do it over e-mail, LinkedIn, Facebook, Twitter, etc., as I much prefer to have my answer be a public good, accessible to everyone in the future. Moreover, if I am wrong, someone will usually come along to correct me, which is much better for everyone involved. Create a simpler reproducible example on one of the toy data sets that demonstrates the problem you are having, put that up on CrossValidated, and then tag me. I will take a look when I get the chance.