[selectionbias]

(Ignore my previous reply I found it myself). To be fair to the authors, it is not their primary specification, that was a linear probability model. The logit model is just a robustness check to make sure the linearity assumption isn't driving the results.

[ims]

Yes, the primary specification was a linear probability model for the likelihood of a binary dependent variable conditioned on two binary input variables. As far as I could tell, the fit was max likelihood without regularization and the paper's bombshell conclusion was based on the regression coefficients' p-values.

The Stata thing was just one of many, many red flags.

[gwern]

When your robustness check fails because of numerical overflow...