Equilibrium Price Dispersion with Sequential Search

Diamond (1971) showed that in a market where consumers search sequentially and have strictly positive search costs the unique price equilibrium is where all firms charge the monopoly price. This paper demonstrates that Diamond's result depends crucially on the assumption of single commodity search and does not persist when the model is generalised to allow multi-commodity search. A model is presented where identical consumers search optimally (sequentially) and with positive search costs for two commodities. Firms supply only one of the commodity types so consumers are required to sample at least two firms to satisfy their consumption requirements. Within industries firms are identical, producing a homogenous product at the same, constant, marginal cost. The equilibrium is shown to display price dispersion, in fact no two firms charge the same price with positive probability. Comparative statics are conducted and it is demonstrated that the price dispersion depends solely on the search behaviour of consumers, converging to the competitive price as search costs converge to zero. Changes in industry demand effect equilibrium prices only through the indirect impact the change in demand has on the consumers search behaviour.

Online Price Dispersion Within and Between Seven European Countries

This paper provides a comprehensive analysis of online price dispersion in Europe, across a broad range of product categories and countries. Using the dominant European price comparison site we collected firm specific prices, weekly, from sevcn European countries (Denmark, France, Italy, Netherlands, Spain, Sweden and the United Kingdom) for 31 unique products, falling into five distinct product categories (printers, PDAs, scanners, games consoles, computer games and music), over the nine month period October 2001 to June 2002. The resulting data set comprises over 17,000 individual price observations. Using a number of alternative measures of price dispersion we find significant differences in the degree of price dispersion observed in online markets, both between countries and across product categories. We consider alternative explanations for online price dispersion and analyse their significance in explaining the observed differences

Reduction of noise in gyro outputs

Technique is described to reduce extraneous gyro output signals by using relatively inexpensive shrouds which do not increase power comsumption. Shrouds reduce noise by minimizing mass of gas spinning with rotor, reducing Reynolds number near rotor, and inducing laminar flow