We propose a framework for analyzing transformations of demand. Such transformations frequently stem from changes in the dispersion of consumers` valuations, which lead to rotations of the demand curve. In a wide variety of settings, profits are a U-shaped function of dispersion. A high level of...

Firms selling multiple quality-differentiated products frequently alter their product lines when a competitor enters the market. We present a model of multiproduct monopoly and duopoly using a general `upgrades` approach that yields a powerful analytical framework. We provide a simple...

We present a general Cournot model in which each firm may sell multiple quality-differentiated products. We use an upgrades approach, working not with the actual products, but instead with upgrades from one quality to the next. The properties of single-product Cournot models carry over to the...

Expansion in mobile phone coverage has improved access to information throughout the developing world, particularly within sub-Saharan Africa.  The existing evidence suggests that information technology has improved market efficiency and reduced consumer prices for certain commodities.  There...

We report the short-term results from a randomized evaluation of a mobile phone literacy and numeracy program (Project ABC) in Niger, in which adult literacy students learned how to use mobile phones as part of a literacy and numeracy class.  Students in ABC villages showed substantial gains in...