“…Indeed, we show in the supplementary appendix, via a simple example, that the joint distribution of unobservables cannot be uniquely recovered without the excluded variables, at least in our general formulation of the model. These results clarify the critical, if not surprising, need for choice-specific exclusion restrictions, something that has been exploited in some applications (e.g., Liu, Chintagunta, and Zhu (2010)) but is absent in others (e.g., Kretchsmer, Miravete, and Pernias (2012) and Hartman (2010)).…”