"Zeros" Problems

While not unique to empirical legal scholarship, how to deal with a "zeros problem" is not uncommon, especially given the nature of many research designs and questions in legal scholarship. To take one obvious--and well-trod--example, efforts to model punitive damage awards need to account for their absence in the over-whelming majority of civil cases decided by courts. A recent discussion on the StataList (here) provides yet another take on the array of challenges posed by "zeros" in data sets. The resultant discussions emphasizes, in part, that researchers need to assess with accuracy and clarity, ex ante, precisely what a "zero" means in the context of their data sets. As well, for a recent take on differences between Heckman selection and two-part models, a 2015 JELS paper (here), by Eisenberg et al., remains current.