A Note on the Theme of Too Many Instruments*

The difference and system generalized method of moments (GMM) estimators are growing in popularity. As implemented in popular software, the estimators easily generate instruments that are numerous and, in system GMM, potentially suspect. A large instrument collection overfits endogenous variables even as it weakens the Hansen test of the instruments’ joint validity. This paper reviews the evidence on the effects of instrument proliferation, and describes and simulates simple ways to control it. It illustrates the dangers by replicating Forbes [American Economic Review (2000) Vol. 90, pp. 869–887] on income inequality and Levine et al. [Journal of Monetary Economics] (2000) Vol. 46, pp. 31–77] on financial sector development. Results in both papers appear driven by previously undetected endogeneity.     

Tourism Policy Making:: The Policymakers’ Perspectives

This research explores tourism policy making, from the perspectives of policy makers using grounded theory. It focuses on Leeds, a city in the North of England, which is characterized by its turbulent environment. The paper identifies themes around policy making, including low status, lack of clarity, uncertainty, lack of consensus and congruence and complexity. Its findings indicate policy making is essentially a social process, involving communication and negotiation between people in the context of wider change. It suggests a social conceptualization, and further research to investigate the communications involved in producing policy rather than the focus on the tangible outputs of the process such as a plan or a physical development.     

Homeownership and Child Welfare

Recent studies have concluded that homeownership is beneficial to children. This result is important because it is used to justify large government subsidies that encourage homeownership. We reexamine the results of two of the most prominent of these studies using the Panel Study of Income Dynamics, Public Use Microsample, and National Longitudinal Survey of Youth data. We extend this research by controlling for residential mobility, wealth, dwelling type and vehicle ownership, as well as by using a "differences in differences" methodology to deal with possible treatment effects bias. We find that the beneficial effects of homeownership previously measured are substantially reduced or eliminated by controlling for these factors. We confirm these results using data from the Early Childhood Longitudinal Study.     

Policy Implications of the Effects of Concentration and Multimarket Contact in China’s Airline Market

Unlike many other mergers in developed countries, which might have been assessed and their effects estimated by antitrust authorities before being granted antitrust immunity, the airline mergers that swept China’s airline industry in 2002 occurred with no antitrust challenge. These mergers provide the opportunity to study important market power issues in China’s airline markets. Given that increased concentration and multimarket contact are the main legacies of an airline merger, the effects of mergers on these variables can raise the potential for the exercise of market power. However, an examination of the period 2002–2004 during which the Chinese airline mergers occurred shows that the resulting increased concentration and enhanced multimarket contact did not have important consequences for airfares in Chinese city-pair markets. The presence of Hainan Airlines appears to have played an important role in suppressing the airfares charged by China Eastern and China Southern.     

Running From a Bear: How Poor Stock Market Performance Affects the Determinants of Mutual Fund Flows

Abstract:  Using a proprietary data set to study how past performance affects the determinants of mutual fund flows for a sample of load fund investors, I provide evidence that the determinants of fund flow depend on market conditions for both redemptions and purchases. Specifically, I show that, for redemptions, relative performance and risk adjusted performance are important determinants during a period of record flows into mutual funds. Conversely, during a period of poor performance, absolute performance becomes much more important and relative performance and risk adjusted performance become less important. For purchases, absolute performance, risk adjusted performance, and most relative performance measures become more important during the bear market.     

Exclusive contracts foster relationship‐specific investment

Exclusive contracts prohibit one or both parties from trading with anyone else. Contrary to earlier findings, we show that investments that are specific to the contracting parties may be encouraged by exclusivity. Results depend on the nature of investments and the bargaining solution. The major part of the analysis shows that exclusivity deals designed to “assure” the supply of essential inputs promote investment. Infinite penalties for breach, even if ex post renegotiable, may result in excessive investment, in which case a positive but finite damage payment yields the first‐best outcome.     

On-Line Portfolio Selection Using Multiplicative Updates

We present an on-line investment algorithm that achieves almost the same wealth as the best constant-rebalanced portfolio determined in hindsight from the actual market outcomes. The algorithm employs a multiplicative update rule derived using a framework introduced by Kivinen and Warmuth. Our algorithm is very simple to implement and requires only constant storage and computing time per stock in each trading period. We tested the performance of our algorithm on real stock data from the New York Stock Exchange accumulated during a 22-year period. On these data, our algorithm clearly outperforms the best single stock as well as Cover's universal portfolio selection algorithm. We also present results for the situation in which the investor has access to additional "side information."     

Quantifying Price Liberalization in Russia

We seek to quantify the success of Russia's attempt to achieve price-liberalization initiatives as part of the reforms established under the Big Bang of January 1992. We do so by studying the time-series behavior of commodity prices between 1992–1995 and focusing on the relationship between the behavior of prices of similar goods within and across cities. We supplement this analysis by examining city-level surveys that seek to quantify the extent to which firms are currently able to set and adjust commodity prices in accordance with market conditions. Our evidence suggests that price liberalization gradually gained momentum following the Big Bang and that prices generally reflected market conditions by the first quarter of 1995. However, regional pockets of resistance to price-reform efforts continue to persist, indicating that Russia has yet to achieve full market integration.J. Comp. Econom.,December 1998, 26(4), pp. 735–760. University of Pittsburgh, Pittsburgh, Pennsylvania 15260.     

Individual versus institutional investors and the weekend effect

Since the late 1980’s, considerable research has focused on the behavior of individual versus institutional investors and the potential patterns which may emerge from their trading activities. Miller (1988) and Abraham and Ikenberry (1994) posit that the tendency for negative Monday returns on equity (i.e., the weekend effect) is at least partially explained by the trading behavior of individual investors. Sias and Starks (1995), on the other hand, present empirical evidence showing a dominant role played by institutional traders. This study contributes to the literature by distinguishing between individual versus institutional trading as it relates to the weekend effect. We find that the information-processing hypothesis is consistent with observed institutional trading patterns, thus supporting the results of Sias and Starks (1995). In addition, these results are shown to be robust with respect to market type (i.e., auction and dealer markets).