<Emphasis Type="Italic">K</Emphasis>-fold cross validation performance comparisons of six naive portfolio selection rules: how naive can you be and still have successful out-of-sample portfolio performance?

Recent research reports that optimal portfolio selection models often perform worse than equal-weight naive diversification in out-of-sample testing. This paper extends this line of inquiry by comparing the out-of-sample performance of the equal-weight naive strategy to the out-of-sample performance of five alternative naive strategies, each of which derives from a simple heuristic that does not require any optimization. Out-of-sample portfolio performance is assessed by mean, standard deviation, skewness, and Sharpe ratio; k-fold cross validation is used as the out-of-sample testing mechanism. The results indicate that the proposed naive heuristic rules exhibit strong out-of-sample performance, in most cases superior to the equal-weight naive strategy. These findings are consequential for at least two reasons: first, if these simple heuristic-based rules outperform the equal-weight naive strategy, then by transitivity they can outperform the mean–variance- and shortfall-optimal portfolio rules that have been shown in the literature to be inferior to the equal-weight naive rule, which further emphasizes the out-of-sample fragility of “optimal” methods; and second, among naive diversification strategies, some appear more robust in out-of-sample testing than others, hence the proposed methods may be useful when forming mixed portfolio selection models wherein a naive strategy is combined with an optimal strategy to improve performance.     

ETF Competition and Market Quality

This paper examines competition between exchange traded funds (ETFs) that hold nearly identical portfolios of securities. We provide evidence that incumbent‐fund liquidity is negatively affected when a new ETF is added to an asset class. The degradation in liquidity is even more severe whenever both funds follow the same benchmark. We also document a decline in primary‐market activity for the incumbent ETFs after the arrival of new competitors. Furthermore, increasing the number of funds in an asset class does not put downward pressure on fund management fees. Thus, the deterioration in market quality may not be offset by decreasing costs of fund ownership.     

Optimum government credibility in an open-economy fiscal expansion

A real open-economy model is constructed in which the government's commitment to a future fiscal expansion is not credible. Government credibility (measured by the growth rate of the probability that the expansion will occur) becomes a parameter of the system and appears directly in the eigenvalues. Simulations are performed demonstrating the effect of credibility on GNP, the exchange rate, and other variables. Lastly, the optimum credibility is determined which minimizes a loss function associated with deviations from full employment.     

Tourist experiences,phenomenographic analysis,post‐postivism and neural network software

This paper argues that tourist experiences are essentially individualistic, although it is possible to discern consensual realties. It follows the viewpoint that positivistic research methodologies contain limitations in not being able to define the nature of individual tourist experience, and suggests that phenomenographic analysis may be one approach that permits both a revelation of individual experience while permitting model building of the shared consensus of what is actually happening. More tentatively it is suggested that, when allied with the use of current developments in software, such as that of CATPAC™, a post‐positivist paradigm of research results. Some results of research using this approach are indicated. Copyright © 2000 John Wiley & Sons, Ltd.     

A post-carbon aviation future: Airports and the transition to a cleaner aviation sector

There is an increasing global interest in sustainable aviation technologies as a result of concerns associated with the carbon-intensive nature of the industry and the imminence of reaching peak oil. Available options such as biofuels, liquid hydrogen and electric propulsion will not only impact on the design and functionality of commercial airplanes, but also will affect the entire industry from supply through to operation and maintenance. However, on account of the global spread and international nature of aviation, in addition to the lock-in effect associated with existing fossil-fuel driven technology, the present aviation paradigm is not well equipped for a massive or rapid technological transition. This paper first provides an overview of selected available propulsion options, as well as their possible impact on the aviation infrastructure. It then sets out to identify the existing regime players in the aviation transition arena as a means to provide an overview of potential path trajectories, with a view to assessing how airport owners and other salient regime players can either facilitate or hinder the transition to alternative and less carbon-intensive technologies.     

What is going on when nothing is going on? Exploring the role of the consumer in shaping waiting situations

Research on waiting in services focuses mainly on the role of companies in waiting situations. Much of the existing research envisages the consumer as a passive victim of the delays caused by companies. This article redresses the imbalance in research on waiting by exploring the role of consumers in waiting situations. A qualitative methodology is used, involving data collection through in‐depth interviews and personal diaries, to facilitate an in‐depth analysis of consumers’ waiting experiences. Additionally, a holistic approach is employed with a view to examining the ‘whole’ waiting experience rather than individual or isolated aspects of waiting. The main finding of the study is that consumers play an active and deliberate role in waiting situations. This is the first study to empirically identify the behaviours and initiatives undertaken by consumers when forced to wait for services. The results suggest that consumers play an active role in organising and reducing the real or perceived waiting time. They actively seek information on the length and causes of the wait. And, on occasions, the consumer may also be the cause of the wait or may even increase the delay by their actions. In contrast to most of the existing research on the topic of waiting, this study adopt a qualitative, in‐depth approach, with a multicultural sample, and a focus on the consumer whose role in waiting has previously been overlooked.     

Profiling road transport activity: Emissions from 2000 to 2005 in Ireland using national car test data

This work describes a methodology for determining the average vehicle kilometres travelled by the private national car fleet in Ireland and estimating the disaggregated CO₂ and NO_x emissions from private vehicles in the Irish road transport sector for the period 2000–2005 using national car test records. The developed methodology facilitates the calculation of greatly improved estimates for vehicle kilometres under a range of constraint variables and thereby enables the disaggregated analysis of specific vehicle fleet groups and their associated activity patterns to support evidence-based policy development. The results indicate that while older vehicles are contributing significantly to car NO_x emissions; newer cars produce a higher share of CO₂ emissions than older cars in the vehicle fleet.     

Marxism,Crypto-Marxism and the Political Economy of Capitalism

ABSTRACT

This article conducts groundwork for a discussion of Marx’s influence through examining the boundaries of the specifically Marxian school of economics. This Marxian school extends well beyond the bounds of the self-identified Marxian school. Marx’s influence, Marxian themes and effectively Marxian theory can be found in several important heterodox traditions of economics, though this is often unacknowledged. A consideration of the proper boundaries of the Marxian school of economics is essential for a full understanding of Marx’s legacy and could contribute to the emergence of a more unified heterodoxy in economics.