A Simple Panel‐CADF Test for Unit Roots*

In this paper, we propose a simple extension to the panel case of the covariate‐augmented Dickey–Fuller (CADF) test for unit roots developed in Hansen (1995) . The panel test we propose is based on a P values combination approach that takes into account cross‐section dependence. We show that the test has good size properties and gives power gains with respect to other popular panel approaches. An empirical application is carried out for illustration purposes on international data to test the purchasing power parity (PPP) hypothesis.     

Response to De Vroey

Abstract

This paper is a response to Michel De Vroey's review of our book, published in this issue of EJHET. Differently from De Vroey's, our aim is to understand the theoretical choices with which economists believed they were confronted at the time. This is reflected in the organisation of our book, the selection of topics (disequilibrium, imperfect competition, etc.), and the conclusions about the fate of disequilibrium macroeconomics.     

Using System Dynamics to assess the impact of RFID technology on retail operations

The application of item-level radio frequency identification (RFID) technology in retail supply chains creates cost savings and promises large potential benefits from revenue growth. However, the economic assessment of the impact on improved store operations, labor utilization, and increased sales is still not fully explored. We propose to use System Dynamics as a structural modeling and simulation approach to integrate conventional return on investment evaluations. Building on previous research about RFID technology in retail supply chains, we developed a model based on the case exploration of a leading Italian apparel retailer. Simulations show that RFID implementations are profitable whenever they contribute to increase sales, especially when a fashion retailer is focused on clerk-assisted sales strategies. Sales growth results from the dynamic and integrated impacts of RFID technology on better inventory control, faster inventory turnover, and longer time available for store personnel to assist consumers as an effect of more efficient backroom operations.     

Cournot model of brokered FX trading

This paper develops a Cournot model of rival dealers placing limit orders with a broker, who in turn makes a market by acting as a liaison between dealers. The broker's limit-book lists the various prices and quantities at which dealers are willing to exchange currency vis-à-vis electronic broking. The size and volatility of the inside spread is simulated relative to dealer entry–exit and the price elasticity of linear order arrival functions. Our simulations reveal non-linear price dynamics from dealer participation in market development, with an additional rival narrowing the inside spread by 1.82% while diminishing its volatility. These findings may shed some light on the “excess volatility puzzle” raised by Killeen, Lyons and Moore (forthcoming) as to why price behavior under flexible exchange rate regimes is significantly more volatile than macro fundamentals would suggest.     

Exports versus FDI: An Empirical Test

In a recent paper Helpman, Melitz and Yeaple argue firm heterogeneity leads to self-selection in the structure of international commerce. Only the most productive firms find it profitable to meet the higher costs associated with FDI; the next set of firms finds it profitable to serve foreign markets through exporting; while the least productive firms serve only the domestic market. The paper tests this assumption using the concept of stochastic dominance. Robust support is found for the model, the productivity distribution of multinational firms is found to dominate that of export firms, which in turn dominates that of non-exporters. JEL no. D24, F14, F23     

WHAT HAPPENED TO THE KNOWLEDGE ECONOMY? ICT,INTANGIBLE INVESTMENT,AND BRITAIN'S PRODUCTIVITY RECORD REVISITED

Despite the apparent importance of the "knowledge economy," U.K. macroeconomic performance appears unaffected: investment rates are flat, and productivity has slowed. We investigate whether measurement issues might account for this puzzle. The standard National Accounts treatment of most spending on "knowledge" or "intangible" assets is as intermediate consumption. Thus they do not count as either GDP or investment. We ask how treating such spending as investment affects some key macro variables, namely, market sector gross value added (MGVA), business investment, capital and labor shares, growth in labor and total factor productivity (TFP), and capital deepening. We find: (a) MGVA was understated by about 6 percent in 1970 and 13 percent in 2004; (b) instead of the business investment/MGVA ratio falling since 1970 it has been rising; (c) instead of the labor share being flat since 1970 it has been falling; (d) growth in labor productivity and capital deepening has been understated and growth in TFP overstated; and (e) TFP growth has not slowed since 1990 but has been accelerating.     

Requiem for the unit root in per capita real GDP? Additional evidence from historical data

We present new evidence on the uncertain nature of nonstationarity – that is, trend stationarity vs. difference stationarity – of aggregate per capita real output, by submitting to a composite testing procedure a 20-country sample over an historically relevant time span. We find that the degree of uncertainty associated with the presence of a unit root appears to be well exceeding that shown by other studies conducted so far on cross-country historical data. For almost all the countries in our sample, inference appears to be strongly dependent on the type of test one makes use of, so that conclusions reached at early stages of a composite confirmatory testing procedure have to be frequently discarded at subsequent stages. Our reading of these findings points towards rejecting the assumption of temporal homogeneity of per capita GDP time series over long time spans, a prerequisite implicitly assumed in all studies looking for invariant statistical properties like stochastic or deterministic nonstationarity.First version received: October 2002/Final version received: September 2003     

The impact of buyer-supplier relationship quality and information management on industrial vending machine benefits in the healthcare industry

Despite the calls for a deeper understanding of SCM in the healthcare industry, theoretical research focused on healthcare buyer-supplier collaboration, specifically inventory management issues, remains nascent and fragmented. Although slow to change, healthcare organizations have begun to consider alternative inventory management systems to improve inventory control and patient care. Industrial vending machines (IVM) can help healthcare organizations address inventory management issues. Grounded in transaction cost economics and contingency theory, this research develops and empirically tests a model that highlights the critical role of information management in the link between buyer-supplier relationship quality and performance outcomes within the context of IVM implementation and use in the healthcare industry. Based on survey data from healthcare managers, results indicate that both information management and relationship quality are tied to a series of benefits in the context of collaborative buyer-supplier IVM agreements.     

Differentiated oligopolistic markets with concave cost functions via Ky Fan inequalities

A Nash–Cournot model for oligopolistic markets with concave cost functions and a differentiated commodity is analyzed. Equilibrium states are characterized through Ky Fan inequalities. Relying on the minimization of a suitable merit function, a general algorithmic scheme for solving them is provided. Two concrete algorithms are therefore designed that converge under suitable convexity and monotonicity assumptions. The results of some numerical tests on randomly generated markets are also reported.