Existence and Persistence of Price Dispersion: an Empirical Analysis

Using a unique data set on store-level monthly prices of four homogenous products sold in Israel, I study the existence and characteristics of the dispersion of prices across stores, as well as its persistence over time. I find that price dispersion prevails even after controlling for observed and unobserved product heterogeneity. Moreover, intra-distribution mobility is significant: stores move up and down the cross-sectional price distribution. Thus, consumers cannot learn about stores that consistently post low prices. As a consequence, price dispersion does not disappear and persists over time as predicted by Varian's (1980) model of sales.

Non-Contact Friction for Ion-Surface Interactions

Non-contact friction forces are exerted on physical systems through dissipative processes, when the two systems are not in physical contact with each other, or, in quantum mechanical terms, when the overlap of their wave functions is negligible. Non-contact friction is mediated by the exchange of virtual quanta, with the additional requirement that the scattering process needs to have an inelastic component. For finite-temperature ion-surface interactions, the friction is essentially caused by Ohmic resistance due to the motion of the image charge moving in a dielectric material. A conceivable experiment is difficult because the friction force needs to be isolated from the interaction with the image charge, which significantly distorts the ion's flight path. We propose an experimental setup which is designed to minimize the influence of the image charge interaction though a compensation mechanism, and evaluate the energy loss due to non-contact friction for helium ions (He+) interacting with gold, vanadium, titanium and graphite surfaces. Interactions with the infinite series of mirror charges in the plates are summed in terms of the logarithmic derivatives of the Gamma function, and of the Hurwitz zeta function.Comment: 9 pages; ReVTeX; accepted for publication in Eur.Phys.J.

The Interaction Between Capital Investment and R&D in Science-Based Firms

This paper analyzes the interaction among R&D, capital investment , and the stock market rate of return for 191 firms in science-based industries for the period 1973-1981. Using a framework based on dynamic factor analysis, we show how several prominent hypotheses about the determination of R&D and investment generate testable parameter restrictions. The data indicate that R&D Granger-causes investment, but that investment does not Granger-cause R&D. We use this finding to examine the validity of those hypotheses, to characterize the movements over time of R&D and investment, and to measure the stock market valuation of these movements.

Incentives and Invention in Universities

We show that economic incentives affect the number and commercial value of inventions generated in universities. Using panel data for 102 U.S. universities during the period 1991-1999, we find that universities which give higher royalty shares to academic scientists generate more inventions and higher license income, controlling for other factors including university size, quality, research funding and technology licensing inputs. The incentive effects are much larger in private universities than in public ones. For private institutions there is a Laffer curve effect: raising the inventor's royalty share increases the license income retained by the university. The incentive effect appears to work both through the level of effort and sorting of academic scientists.

Linear versus nonlinear causalityfor dax companies

This study provides empirical evidence of the joint dynamics between stock returns and trading volume using stock data for DAX companies. Our research confirms the hypothesis that traditional linear causality tests often fail to detect some kinds of nonlinear relations, while nonlinear tests do not. In many cases, the test results obtained by use of empirical data and simulation confirm a bidirectional causal relationship, while linear tests did not detect such causality at all.DAX companies, stock returns, trading volume, linear and nonlinear causality, simulation

Accelerators Beyond The Tevatron?

Following the successful operation of the Fermilab superconducting accelerator three new higher energy accelerators were planned. They were the UNK in the Soviet Union, the LHC in Europe, and the SSC in the United States. All were expected to start producing physics about 1995. They did not. Why?Comment: Presented at SIMPOSIO CINVESTAV-UNAM In Memoriam AUGUSTO GARCIA (1942-2009

Incentives and Invention in Universities

We show that economic incentives affect the commercial value of inventions generated in universities. Using data for 102 U.S. universities during the period 1991-1999, we find that universities which give higher royalty shares to academic scientists generate higher license income, controlling for other factors including university size, quality, research funding and technology licensing inputs. We provide evidence that this is due to the fact that public universities are less effective at commercialising inventions, which weakens the incentive effect of higher royalty shares. Other findings include: 1) there is a Laffer effect in private universities: raising the inventor's royalty share increases the license income retained by the university; 2) the incentive effect works primarily by increasing the quality of inventions, and 3) the incentive effect appears to operate both by raising faculty effort and by sorting academic scientists across universities.Academic research, incentives, licensing, royalties, technology transfer, intellectual property.

Measuring Temporary Labor Outsourcing in U.S. Manufacturing

Several analysts claim that firms have been using more flexible work arrangements in order to contain the costly adjustment of labor to changes in economic conditions. In particular, temporary help supply (THS) employment has increased dramatically in the last ten years. However, there is only scant evidence on the industries that are hiring this type of worker. In particular, some anecdotal evidence points to the fact that manufacturing industries have substantially stepped up their demand for THS workers since the mid-1980s. If this is true, not accounting for this flow of workers from the service sector to manufacturing may lead to misleading conclusions about the cyclical and long-term path of manufacturing employment and hours of work. We close this gap by providing several estimates of the number of individuals employed by temporary help supply (THS) firms who worked in the manufacturing sector from 1972 to 1997. One estimate, in particular, is based on a new methodology that uses minimal assumptions to put bounds on the probability that a manufacturing worker is employed by a THS firm. The bounds rely on readily available data on workers' individual characteristics observable in the CPS. We show that manufacturers have been using THS workers more intensively in the 1990s. In addition, the apparent flatness of manufacturing employment in the 1990s can be explained in part by this type of outsourcing from the service sector. Finally, not accounting for THS hours overstated the increase in average annual manufacturing labor productivity by « percentage point during the 1991-1997 period.