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Better Capture (good + capture)
Selected AbstractsEmpirical assessment of a collaborative filtering algorithm based on OWA operatorsINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 12 2008Miguel-Angel Sicilia Classical collaborative filtering algorithms generate recommendations on the basis of ratings provided by users that express their subjective preference on concrete items. The correlation of ratings is used in such schemes as an implicit measure of common interest between users, that is used to predict ratings, so that these ratings determine recommendations. The common formulae used for the computation of predicted ratings use standard weighted averaging schemes as the fixed aggregation mechanism that determines the result of the prediction. Nonetheless, the surrounding context of these rating systems suggest that an approach considering a degree of group consensus in the aggregation process may better capture the essence of the "word,of,mouth" philosophy of such systems. This paper reports on the empirical evaluation of such an alternative approach in which OWA operators with different properties are tested against a dataset to search for the better empirical adjustment. The resulting algorithm can be considered as a generalization of the original Pearson formula based algorithm that allows for the fitting of the aggregation behavior to concrete databases of ratings. The results show that for the particular context studied, higher orness degrees reduce overall error measures, especially for high ratings, which are more relevant in recommendation settings. The adjustment procedure can be used as a general-purpose method for the empirical fit of the behavior of collaborative filtering systems. © 2008 Wiley Periodicals, Inc. [source] An investigation of incident frequency, duration and lanes blockage for determining traffic delayJOURNAL OF ADVANCED TRANSPORTATION, Issue 3 2009Yi (Grace) Qi Traffic delay caused by incidents is closely related to three variables: incident frequency, incident duration, and the number of lanes blocked by an incident that is directly related to the bottleneck capacity. Relatively, incident duration has been more extensively studied than incident frequency and the number of lanes blocked in an incident. In this study, we provide an investigation of the influencing factors for all of these three variables based on an incident data set that was collected in New York City (NYC). The information about the incidents derived from the identification can be used by incident management agencies in NYC for strategic policy decision making and daily incident management and traffic operation. In identifying the influencing factors for incident frequency, a set of models, including Poisson and Negative Binomial regression models and their zero-inflated models, were considered. An appropriate model was determined based on a model decision-making tree. The influencing factors for incident duration were identified based on hazard-based models where Exponential, Weibull, Log-logistic, and Log-normal distributions were considered for incident duration. For the number of lanes blocked in an incident, the identification of the influencing factors was based on an Ordered Probit model which can better capture the order inherent in the number of lanes blocked in an incident. As identified in this study, rain is the only factor that significantly influenced incident frequency. For incident duration and the number of lanes blocked in an incident, various factors had significant impact. As concluded in this study, there is a strong need to identify the influencing factors in terms of different types of incidents and the roadways where the incidents occured. [source] Using the PRISM to Compare the Explanatory Value of General and Role-Contextualized Trait RatingsJOURNAL OF PERSONALITY, Issue 6 2007Dustin Wood ABSTRACT In an earlier work (Wood & Roberts, 2006), the Personality and Role Identity Structural Model (PRISM) was proposed as a model for organizing the relations between diverse self-perceptions, with a person's general identity ("how I am in general") organized above diverse role identities (e.g., "how I am as an employee"), which in turn is organized above role-specific behaviors and experiences (e.g., typical interactions with coworkers). In the present article, I argue that despite the fact that role trait measures are often much more related to role behaviors than general trait measures in cross-sectional analyses, general trait measures better capture the dispositional causes of a person's role behavior. In support of this, a brief study is presented illustrating how general traits may be better predictors than role-contextualized trait ratings of the evolution of an individual's experiences or behaviors within a given context. Finally, I contend that the basic framework of the PRISM, where a person's behaviors and identities within multiple contexts are assessed simultaneously and longitudinally alongside general personality ratings, is necessary to make strong statements concerning the nature of the relationships between personality traits and role experiences. [source] Emerging patterns in the comparative analysis of phylogenetic community structureMOLECULAR ECOLOGY, Issue 4 2009S. M. VAMOSI Abstract The analysis of the phylogenetic structure of communities can help reveal contemporary ecological interactions, as well as link community ecology with biogeography and the study of character evolution. The number of studies employing this broad approach has increased to the point where comparison of their results can now be used to highlight successes and deficiencies in the approach, and to detect emerging patterns in community organization. We review studies of the phylogenetic structure of communities of different major taxa and trophic levels, across different spatial and phylogenetic scales, and using different metrics and null models. Twenty-three of 39 studies (59%) find evidence for phylogenetic clustering in contemporary communities, but terrestrial and/or plant systems are heavily over-represented among published studies. Experimental investigations, although uncommon at present, hold promise for unravelling mechanisms underlying the phylogenetic community structure patterns observed in community surveys. We discuss the relationship between metrics of phylogenetic clustering and tree balance and explore the various emerging biases in taxonomy and pitfalls of scale. Finally, we look beyond one-dimensional metrics of phylogenetic structure towards multivariate descriptors that better capture the variety of ecological behaviours likely to be exhibited in communities of species with hundreds of millions of years of independent evolution. [source] In search of the wage-labour/service contract: new evidence on the validity of the Goldthorpe class schemaTHE BRITISH JOURNAL OF SOCIOLOGY, Issue 4 2000Geoffrey Evans ABSTRACT In this paper we examine new empirical evidence on the coherence and magnitude of the main classes in the Goldthorpe class schema. Particular attention is paid to issues that have recently been a source of academic dispute: the coherence and size of the service class and the distinction between the service class and intermediate classes. Using recently available British data collected by the Office for National Statistics we examine: (i) the extent to which measures of class-relevant job characteristics are empirically discriminated by the categories of the schema; (ii) the structure of a ,contract type' dimension of employment relations conceived of as a categorical latent variable; and (iii) the association between this latent variable and both the Goldthorpe class schema and a related measure,socio-economic group (SEG). We find that the data are consistent with the existence of a three category latent ,contract type' variable largely corresponding to the notions of service, intermediate and wage-labour contracts explicit in discussions of the theoretical rationale for the Goldthorpe schema. We further find a substantial degree of fit between the latent ,contract types' and the schema. However, the service class fault line appears to lie within class I and II of the schema rather than between them and the intermediate classes which suggests a revised, smaller service class would better capture the reality of the contemporary British occupational structure. [source] Specification Analysis of Option Pricing Models Based on Time-Changed Lévy ProcessesTHE JOURNAL OF FINANCE, Issue 3 2004Jing-zhi Huang We analyze the specifications of option pricing models based on time-changed Lévy processes. We classify option pricing models based on the structure of the jump component in the underlying return process, the source of stochastic volatility, and the specification of the volatility process itself. Our estimation of a variety of model specifications indicates that to better capture the behavior of the S&P 500 index options, we need to incorporate a high frequency jump component in the return process and generate stochastic volatilities from two different sources, the jump component and the diffusion component. [source] Combustion modeling of blended coal in a 300-MW tangentially fired boiler using a two-mixture-fraction modelASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2009Qing-Yan Fang Abstract The combustion process in a 300-MW tangentially fired boiler furnace fired with a blended coal has been numerically simulated. The blended coal contains a low-quality bituminous coal and anthracite and it was injected into the furnace from different burner nozzles. In order to better capture the combustion characteristics, a two-mixture-fraction model has been developed to model the combustion process of each individual coal of the blend. The two mixture fractions were used to separately track the combustion processes of the two component coals to reveal the effect of the combustion of the two coals on the chemical reactions in local zones of the furnace. The sum of the two mixture fractions was used to calculate the gas-phase turbulent combustion. Temperature measurements in the furnace were carried out by a flame image processing technique for model validation. Simulation results show that the temperature and oxygen concentration on the horizontal cross-sections close to the primary air burner nozzles in the furnace are nonuniformly, but symmetrically distributed across the four corners. The temperatures predicted by the simulation agree well with those measured by the flame image processing technique with a maximum error of 8.65%. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Assessing alcohol guidelines in teenagers: results from a 10-year prospective studyAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 2 2009Elya Moore Abstract Objective: To assess the value of drinking guidelines applied in adolescence for predicting alcohol-related outcomes in young adulthood. Methods: We conducted an eight-wave, population-based cohort study of 696 males and 824 females in Victoria between 1992 and 2003. Adolescent drinking was assessed at five survey waves, in six month intervals, from mean age 15.4-17.4 years. We created three measures of adolescent alcohol use using categories from NHMRC drinking guidelines: risky/high-risk drinking in the short and long term (2001), and high-risk drinking (2007). Each measure was defined according to the number of waves at which drinking was reported at or above the designated level during adolescence: non-drinkers, zero waves (low-risk drinkers), one wave, and 2+ waves. Alcohol use disorders and alcohol-related sexual behaviours were assessed at mean age 24.1 years. Results: Fourteen per cent of males and 17% of females were non-drinkers during adolescence. Using each NHMRC drinking guideline, the prevalence of each outcome for men increased with the number of waves at which drinking was reported above the low-risk level (p-values <0.007). The association was less clear for women. The prevalence of each outcome was lower among the nondrinkers compared to the low-risk drinkers for both men and women. Conclusions and implications: These findings support the emphasis in the NHMRC guidelines on abstaining from alcohol during the adolescent years. Any drinking, even at the low-risk level, may not be appropriate in adolescence. However, refinements that could better capture the risk of adolescent drinking in women would be useful. [source] Collective Action Meets Prospect Theory: An Application to Coalition Building in Chile, 1973,75POLITICAL PSYCHOLOGY, Issue 3 2004Maria Fanis Expected utility theory explains collective action as an attempt by individuals to maximize their gains. In contrast, my application of prospect theory to collective action suggests that people are motivated to participate in collective action by a fear of loss. These alternative rationalities are considered in the context of the successful cooperative effort of four economic groups in Chile during 1973,75, the first years of the Pinochet military regime. In this case, the logic of prospect theory better captures how actors made decisions about whether or not to engage in collective action. Of the four groups that did join the 1973,75 economic coalition, only one (the mineowners) appears to have maximized its net asset level, as expected utility theory predicts. All four groups seem to have been motivated to cooperate because they found themselves in the domain of losses and expected that cooperation with other, even rival, economic groups might help them recoup their recent losses. [source] Presidential-Congressional Budget Agreement, 1949,1995POLITICS & POLICY, Issue 3 2001Steven A. Shull In this paper, presidential-congressional budget agreement, measured as the percentage of presidential budget requests appropriated by Congress, is explained. Budget agreement reflects a pivotal point in the struggle between the president and the Congress to enact their respective preferences since funding brings such preferences to life. In order to explain budget agreement, the existing tandem institutions approach to studying presidential-congressional relations is expanded by positing a multiple perspective encompassing a three environment model: executive, legislative and exogenous environments. Three variables tap each institutional environment, comprised of the executive and the legislative, and two variables are included in the exogenous environment. Findings reflect that a multiple perspectives approach better captures the complexities of presidential-congressional relations than a strictly institutional approach. The institutional resources available to both the president and Congress contribute little, but the exogenous environment has the greatest influence on budget agreement. Differences in explanation are observed when budget agreement is divided by domestic and foreign policy. [source] Innovation and corporate sustainability: An investigation into the process of change in the pharmaceuticals industryBUSINESS STRATEGY AND THE ENVIRONMENT, Issue 5 2001Martina Blum-Kusterer Although there has been considerable research effort directed at refining the content of corporate environmental performance, e.g. corporate environmental reporting and accounting, there has been relatively little empirical investigation to date on the process of corporate eco-change. This research reports on the quantitative and qualitative results of a survey of German and UK pharmaceuticals firms, which evaluated the significance of the various incentives, both intra-firm and external to the organization, that have stimulated eco-change. We find that, although the industry is one that has been characterized by voluntary agreements and proactive behaviour in the past, regulation still remains the main driver for sustainability improvements. New technology is the second most important driver. Stakeholder dialogue and inter-firm cooperation were both revealed to be relatively weak forces for eco-change. The study also tested the validity of the conventional neo-classical economic world-view of innovation in firms versus a more radical co-evolutionary one. The former assumes that firms respond only to profit signals and do so efficiently, whereas the latter assumes that change is path dependent; i.e., the firms' norms and routines and past experiences are influential. We find that, although the neo-classical perspective stands up to our empirical investigation of eco-innovation to some degree, the co-evolutionary approach better captures the complexity of the corporate eco-change process. Copyright © 2001 John Wiley & Sons, Ltd. and ERP Environment [source] | ||||||||||