We test the effect of entry on the tariff choices of incumbent cellularfirms. We relate the change in the breadth of calling plans between1996, when incumbents enjoyed a duopoly market, and 1998, whenincumbents faced increased competition from personal communicationsservices (PCS) firms. Entry...

We review recent empirical economic studies on urban ambient air pollution from a mayor’s perspective. We discuss the sources of urban air pollution, the economic costs that it imposes, and the policy tools available to a mayor to alleviate it. For economic costs, we briefly summarize...