The Profitability of Winning

Sports and war metaphors abound in business today. For example, one management book, Thunder in the Sky, by Thomas Cleary, opens with a Chinese saying that translates: “The marketplace is a battlefield. The Asian people view success in the business world as tantamount to victory in battle.” The book advises American executives to do the same. However, such metaphors are misleading. The objective in both sports and war is to beat the competitor. Business, on the other hand, aims to create wealth.business, profits, winning,

Rule-Based Forecasting: Development and Validation of an Expert Systems Approach to Combining Time Series Extrapolations

This paper examines the feasibility of rule -based forecasting, a procedure that applies forecasting expertise and domain knowledge to produce forecasts according to features of the data. We developed a rule base to make annual extrapolation forecasts for economic and demographic time series. The development of the rule base drew upon protocol analyses of five experts on forecasting methods. This rule base, consisting of 99 rules, combined forecasts from four extrapolation methods (the random walk, regression, Brown's linear exponential smoothing, and Holt's exponential smoothing) according to rules using 18 features of time series. For one-year ahead ex ante forecasts of 90 annual series, the median absolute percentage error (MdAPE) for rule- based forecasting was 13% less than that from equally-weighted combined forecasts. For six-year ahead ex ante forecasts, rule-based forecasting had a MdAPE that was 42% less. The improvement in accuracy of the rule - based forecasts over equally-weighted combined forecasts was statistically significant. Rule-based forecasting was more accurate than equal-weights combining in situations involving significant trends, low uncertainty, stability, and good domain expertise.Rule-based forecasting, time series

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Causal Forces: Structuring Knowledge for Time-series Extrapolation

This paper examines a strategy for structuring one type of domain knowledge for use in extrapolation. It does so by representing information about causality and using this domain knowledge to select and combine forecasts. We use five categories to express causal impacts upon trends: growth, decay, supporting, opposing, and regressing. An identification of causal forces aided in the determination of weights for combining extrapolation forecasts. These weights improved average ex ante forecast accuracy when tested on 104 annual economic and demographic time series. Gains in accuracy were greatest when (1) the causal forces were clearly specified and (2) stronger causal effects were expected, as in longer- range forecasts. One rule suggested by this analysis was: “Do not extrapolate trends if they are contrary to causal forces.” We tested this rule by comparing forecasts from a method that implicitly assumes supporting trends (Holt’s exponential smoothing) with forecasts from the random walk. Use of the rule improved accuracy for 20 series where the trends were contrary; the MdAPE (Median Absolute Percentage Error) was 18% less for the random walk on 20 one-year ahead forecasts and 40% less for 20 six-year-ahead forecasts. We then applied the rule to four other data sets. Here, the MdAPE for the random walk forecasts was 17% less than Holt’s error for 943 short-range forecasts and 43% less for 723 long-range forecasts. Our study suggests that the causal assumptions implicit in traditional extrapolation methods are inappropriate for many applications.Causal forces Combining Contrary trends Damped trends Exponential smoothing Judgment Rule-based forecasting Selecting methods

Integration of Statistical Methods and Judgment for Time Series

We consider how judgment and statistical methods should be integrated for time-series forecasting. Our review of published empirical research identified 47 studies, all but four published since 1985. Five procedures were identified: revising judgment; combining forecasts; revising extrapolations; rule-based forecasting; and econometric forecasting. This literature suggests that integration generally improves accuracy when the experts have domain knowledge and when significant trends are involved. Integration is valuable to the extent that judgments are used as inputs to the statistical methods, that they contain additional relevant information, and that the integration scheme is well structured. The choice of an integration approach can have a substantial impact on the accuracy of the resulting forecasts. Integration harms accuracy when judgment is biased or its use is unstructured. Equal-weights combining should be regarded as the benchmark and it is especially appropriate where series have high uncertainty or high instability. When the historical data involve high uncertainty or high instability, we recommend revising judgment, revising extrapolations, or combining. When good domain knowledge is available for the future as well as for the past, we recommend rule- based forecasting or econometric methods.statistical methods, statistics, time series, forecasting, empirical research

Thermal Yang-Mills Theory In the Einstein Universe

We study the stability of a non-Abelian chromomagnetic vacuum in Yang-Mills theory in Euclidean Einstein universe $S^1\times S^3$. We assume that the gauge group is a simple compact group $G$ containing the group SU(2) as a subgroup and consider static covariantly constant gauge fields on $S^3$ taking values in the adjoint representation of the group $G$ and forming a representation of the group $SU(2)$. We compute the heat kernel for the Laplacian acting on fields on $S^3$ in an arbitrary representation of SU(2) and use this result to compute the heat kernels for the gluon and the ghost operators and the one-loop effective action. We show that the only configuration of the covariantly constant Yang-Mills background that is stable is the one that contains only spinor (fundamental) representations of the group SU(2); all other configurations contain negative modes and are unstable. For the stable configuration we compute the asymptotics of the effective action, the energy density, the entropy and the heat capacity in the limits of low/high temperature and small/large volume and show that the energy density has a non-trivial minimum at a finite value of the radius of the sphere $S^3$.Comment: 23 pages, introduction and conclusion are expanded; some references are added. This is the version accepted by J. Phys.

How Serious are Methodological Issues in Surveys? A Reexamination of the Clarence Thomas Polls^T

Opinion polling procedures allow for reasonable inferences about attitude changes. We examined this contention using surveys about the nomination of Clarence Thomas. In this situation, prior theory allowed us to predict the direction of changes, surveys had been conducted by a number of organizations, and substantial information was available about the methodology used in the surveys. As a result we concluded that the deteriorating opinions of Thomas were real.surveys, methodology

The Communal Apartment in the Works of Irina Grekova and Nina Sadur

While a good deal of recent scholarly attention has been paid to the Soviet communal apartment, the current literature has not specifically addressed how women are affected by living in such a space. Russian women have a complicated relationship to the domestic sphere. While the domestic sphere is the center and source of women’s power, cultural and social demands require that women bear almost the entire burden of domestic responsibilities. The present work provides a brief history of the Soviet communal apartment and Russian women’s relationship to the domestic space. The focus then turns to the literary representation of women’s experiences in the communal apartment within the works of two stylistically different Russian women writers, Irina Grekova and Nina Sadur. I argue that despite their differences, both writers portray life in a communal apartment as less than ideal

Designing large systems: Five stories; five lessons

Systems thinking and design practice share the characteristic that to be successful each must concern itself with attending to the needs of the whole and to the interactions among its parts. And they suffer the same fate when they succeed. Inevitably they produce unintended consequences and unanticipated side effects. But there is a radical difference in their typical starting places and their logics