Marketers frequently need to estimate the size of their markets - both for existing products so that sales forecasts can be developed, and for new products so that market opportunities can be assessed. This toolkit enables students to size a market and generate a sales forecast using a market...

This article introduces a newly discovered property of discrete-choice models, which I call the Invariant Proportion of Substitution (IPS). Like the Independence from Irrelevant Alternatives (IIA) property, IPS implies individual behavior that is counterintuitive in the context of choice among...