This paper analyzes the relationship between technological progress, wage inequality, intergenerational earnings mobility, and economic growth. In periods of major technological inventions, a decline in the relative importance of initial conditions raises inequality, enhances mobility, and generates a larger concentration of high-ability individuals in technologically advanced sectors, stimulating future technological progress and growth. However, once technologies become more accessible, mobility is diminished and inequality decreases but becomes more persistent. The reduction in the concentration of ability in technologically advanced sectors diminishes the likelihood of technological break-throughs and slows future growth. User friendliness, therefore, becomes unfriendly to future economic growth.

Theoretical work on price-setting behavior focuses on the single-product case while, in reality, a single price-setter sells many products. We use retail store-level multiproduct pricing data to learn about price dynamics. We find that, while the timing of a product's price changes is staggered across stores selling the same product, the timing of the price changes of different products sold within the same store is highly synchronized. This finding validates the usual assumption that decisions are staggered across price-setters and suggests that price rigidity is due mostly to "mechanical" reasons and not to informational asymmetries.

Most of the theoretical literature on price-setting behavior deals with the special case in which only a single price is changed. At the retail-store level, at least, where dozens of products are sold by a single price-setter, price-setting policies are not formulated for individual products. This feature of economic behavior raises a host of questions whose answers carry interesting implications. Are price setters staggered in the timing of price changes? Are price changes of different products synchronized within the store? If so, is this a result of aggregate shocks or of the presence of a store- specific component in the cost of adjusting prices? Can observed small changes in prices be rationalized by a menu cost model? We exploit the multiproduct dimension of the dataset on prices used in Lach and Tsiddon (1992a) to explore several of these and other issues. To the best of our knowledge this is the first empirical work on this subject.

Endogeneous-growth theory suggests that technological change tends to reinforce the position of the leading nations. Yet sometimes this leadership role shifts. We suggest a mechanism that explains this pattern of "leapfrogging" as a response to occasional major changes in technology. When such a change occurs, the new technology does not initially seem to be an improvement for leading nations, given their extensive experience with older technologies. Lagging nations have less experience; the new technique allows them to use their lower wages to enter the market. If the new technique proves more productive than the old, leapfrogging of leadership occurs.