This Paper focuses on a single simple stylized fact which stands out from the post-war history of the US Car industry, namely that industry concentration fell just at the same time as industry advertising expenditures rose sharply. Since both events were almost certainly caused by the entry and...

This Paper examines four models that might be used to account for variations in the number of producers who operate in a particular market over the lifetime of that market. Two of these are standard economics textbook models, one is a non-standard model and one is a textbook model derived from...