Current Period (current + period)

Distribution by Scientific Domains

Selected Abstracts

Expedient and Monotone Learning Rules

ECONOMETRICA, Issue 2 2004
Tilman Börgers
This paper considers learning rules for environments in which little prior and feedback information is available to the decision maker. Two properties of such learning rules are studied: absolute expediency and monotonicity. Both require that some aspect of the decision maker's performance improves from the current period to the next. The paper provides some necessary, and some sufficient conditions for these properties. It turns out that there is a large variety of learning rules that have the properties. However, all learning rules that have these properties are related to the replicator dynamics of evolutionary game theory. For the case in which there are only two actions, it is shown that one of the absolutely expedient learning rules dominates all others. [source]

Automated generation of new knowledge to support managerial decision-making: case study in forecasting a stock market

EXPERT SYSTEMS, Issue 4 2004
Se-Hak Chun
Abstract: The deluge of data available to managers underscores the need to develop intelligent systems to generate new knowledge. Such tools are available in the form of learning systems from artificial intelligence. This paper explores how the novel tools can support decision-making in the ubiquitous managerial task of forecasting. For concreteness, the methodology is examined in the context of predicting a financial index whose chaotic properties render the time series difficult to predict. The study investigates the circumstances under which enough new knowledge is extracted from temporal data to overturn the efficient markets hypothesis. The efficient markets hypothesis precludes the possibility of anticipating in financial markets. More precisely, the markets are deemed to be so efficient that the best forecast of a price level for the subsequent period is precisely the current price. Certain anomalies to the efficient market premise have been observed, such as calendar effects. Even so, forecasting techniques have been largely unable to outperform the random walk model which corresponds to the behavior of prices under the efficient markets hypothesis. This paper tests the validity of the efficient markets hypothesis by developing knowledge-based tools to forecast a market index. The predictions are examined across several horizons: single-period forecasts as well as multiple periods. For multiperiod forecasts, the predictive methodology takes two forms: a single jump from the current period to the end of the forecast horizon, and a multistage web of forecasts which progresses systematically from one period to the next. These models are first evaluated using neural networks and case-based reasoning, and are then compared against a random walk model. The computational models are examined in the context of forecasting a composite for the Korean stock market. [source]


ABSTRACT Subsequent to the end of the Cold War, analysts groped for an understanding of the overall structures of world politics that marked the emergence of a new epoch. As a result, the concept of empire became a major preoccupation, with the economic and military power of the United States considered sufficient for regarding it as an empire. Due to the proliferation of new microelectronic technologies and for a variety of other specified reasons, however, the constraints inherent in the new epoch make it seem highly unlikely that the U.S. or any other country can ever achieve the status of an empire. In effect, the substantial shrinkage of time and distance in the current period has led to the replacement of the age of the nation-state that originated with the Treaty of Westphalia in 1648 with the age of the networked individual. It is an age that has developed on a global scale and that has brought an end to the history of empires. [source]

Incorporating Penalty Function to Reduce Spill in Stochastic Dynamic Programming Based Reservoir Operation of Hydropower Plants

Deependra Kumar Jha Non-member
Abstract This paper proposes a framework that includes a penalty function incorporated stochastic dynamic programming (SDP) model in order to derive the operation policy of the reservoir of a hydropower plant, with an aim to reduce the amount of spill during operation of the reservoir. SDP models with various inflow process assumptions (independent and Markov-I) are developed and executed in order to derive the reservoir operation policies for the case study of a storage type hydropower plant located in Japan. The policy thus determined consists of target storage levels (end-of-period storage levels) for each combination of the beginning-of-period storage levels and the inflow states of the current period. A penalty function is incorporated in the classical SDP model with objective function that maximizes annual energy generation through operation of the reservoir. Due to the inclusion of the penalty function, operation policy of the reservoir changes in a way that ensures reduced spill. Simulations are carried out to identify reservoir storage guide curves based on the derived operation policies. Reservoir storage guide curves for different values of the coefficient of penalty function , are plotted for a study horizon of 64 years, and the corresponding average annual spill values are compared. It is observed that, with increasing values of ,, the average annual spill decreases; however, the simulated average annual energy value is marginally reduced. The average annual energy generation can be checked vis-à-vis the average annual spill reduction, and the optimal value of , can be identified based on the cost functions associated with energy and spill. © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

The Debate on Globalization, Poverty and Inequality: Why Measurement Matters

Martin Ravallion
In the last year or so, markedly different claims have been heard within the development community about just how much progress is being made against poverty and inequality in the current period of ,globalization'. This article provides a non-technical overview of the conceptual and methodological issues underlying these conflicting claims. It argues that the dramatically different positions taken in this debate often stem from differences in the concepts and definitions used and differences in data sources and measurement assumptions. These differences are often hidden from view in the debate, but they need to be considered carefully if one is properly to interpret the evidence. The article argues that the best available evidence suggests that, if the rate of progress against absolute poverty in the developing world in the 1990s is maintained, then the Millennium Development Goal of halving the 1990 aggregate poverty rate by 2015 will be achieved on time in the aggregate, though not in all regions. The article concludes with some observations on the implications for policy-oriented debates on globalization and pro-poor growth. [source]

Economic Nationalism as a Challenge to Economic Liberalism?

Lessons from the 19th Century
What kind of challenge does economic nationalism pose to economic liberalism in today's global political economy? Conventional wisdom holds that economic nationalism is an outdated ideology in this age of globalization and economic liberalization. But this argument rests on understandings of economic nationalism that are increasingly being called into question by recent scholarship. In this article, I show how the history of economic nationalism in the 19th century provides strong support for two important but potentially controversial arguments made in recent literature about the nature of economic nationalism: (1) that this ideology is most properly defined by its nationalist content (rather than as a variant of realism or as an ideology of protectionism), and (2) that it can be associated with a wide range of policy projects, including the endorsement of liberal economic policies. With these two points established through historical analysis, I conclude that economic nationalism should be seen still to be a powerful ideology in the current period, but that its relationship to the policy goals of economic liberals is an ambiguous one, just as it was in the 19th century. [source]

Land and Social Change in a Tanzanian Village 1: Kinyanambo, 1920s,1990

Elizabeth Daley
This article (in two parts) traces the historical development of land tenure in Kinyanambo village, Mufindi District, Tanzania. It suggests a gradual commoditization of land and the evolution of a predominantly individualized land market, processes influenced by the long-term commoditization of agriculture and social reproduction more generally. Local land tenure practices evolved more or less independently of national land tenure policy until 1974, when villagization altered the evolutionary path of local land tenure, marking a fundamental turning point in people's understandings of their land rights. Together with the simultaneous establishment of Mafinga town, it created conditions for the rapid and more spatially concentrated growth of the local population, for urbanization, and for associated changes in livelihoods, land use, and relations between people and land. As a result, and following the economic reforms of the current period of structural adjustment and liberalization, by 2000 Kinyanambo had a deep-rooted, widespread and socially legitimate market in land. [source]

Your vanishing vendors: Lessons from bank M&As

James S. Sagner
What should corporate clients of banks do during the current period of bank consolidations? The author of this article,a treasury consultant,says that lessons from bank mergers and acquisitions (M&As) can be used by firms whose other vendors are also undergoing mergers. That includes vendors who provide information processing, financial transactions, accounting, tax preparation, and other services. Clients are facing the very real prospect of their long-term vendor relationships vanishing,to be replaced by unknown firms from another part of the globe. © 2010 Wiley Periodicals, Inc. [source]

Dynamic Competition with Experience Goods

J. Miguel Villas-Boas
This paper considers dynamic competition in the case in which consumers are only able to learn about their preferences for a certain product after experiencing it. After trying a product a consumer has more information about that product than about untried products. When competing in such a market firms with more sales in the past have an informational advantage because more consumers know their products. If products provide a better-than-expected fit with greater likelihood, taking advantage of that informational advantage may lead to an informational disadvantage in the future. This paper considers this competition with an infinite horizon model in a duopoly market with overlapping generations of consumers. Two effects are identified: On one hand marginal forward-looking consumers realize that by purchasing a product in the current period will be charged a higher expected price in the future. This effect results in reduced price sensitivity and higher equilibrium prices. On the other hand, forward-looking firms realize that they gain in the future from having a greater market share in the current period and compete more aggressively in prices. For similar discount factors for consumers and firms, the former effect is more important, and prices are higher the greater the informational advantages. The paper also characterizes oscillating market share dynamics, and comparative statics of the equilibrium with respect to consumer and firm patience, and the importance of the experience in the ex post valuation of the product. [source]

Insurer Reserve Error and Executive Compensation

David L. Eckles
This article investigates incentives of insurance firm managers to manipulate loss reserves in order to maximize their compensation. We find that managers who receive bonuses that are likely capped or no bonuses tend to over-reserve for current-year incurred losses. However, managers who receive bonuses that are likely not capped tend to under-reserve for current-year incurred losses. We also find that managers who exercise stock options tend to under-reserve in the current period. [source]

Joint projections of temperature and precipitation change from multiple climate models: a hierarchical Bayesian approach

Claudia Tebaldi
Summary., Posterior distributions for the joint projections of future temperature and precipitation trends and changes are derived by applying a Bayesian hierachical model to a rich data set of simulated climate from general circulation models. The simulations that are analysed here constitute the future projections on which the Intergovernmental Panel on Climate Change based its recent summary report on the future of our planet's climate, albeit without any sophisticated statistical handling of the data. Here we quantify the uncertainty that is represented by the variable results of the various models and their limited ability to represent the observed climate both at global and at regional scales. We do so in a Bayesian framework, by estimating posterior distributions of the climate change signals in terms of trends or differences between future and current periods, and we fully characterize the uncertain nature of a suite of other parameters, like biases, correlation terms and model-specific precisions. Besides presenting our results in terms of posterior distributions of the climate signals, we offer as an alternative representation of the uncertainties in climate change projections the use of the posterior predictive distribution of a new model's projections. The results from our analysis can find straightforward applications in impact studies, which necessitate not only best guesses but also a full representation of the uncertainty in climate change projections. For water resource and crop models, for example, it is vital to use joint projections of temperature and precipitation to represent the characteristics of future climate best, and our statistical analysis delivers just that. [source]