The logit model is the most popular tool for estimating demand in differentiated products markets. However, in its aggregate version, practitioners have to “guess” the size outside good. We propose a way to remove the bias created by an inaccurate guess in simpler versions of the model.

The logit model is the most popular tool in estimating demand for differentiated products. In this model, the outside good plays a crucial role because it allows consumers to stop buying the differentiated good altogether if all brands simultaneously become less attractive (for example if a...