202,465 research outputs found

    Elimination of Bias in Introspection: Methodological Advances, Refinements, and Recommendations

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    Building on past constructive criticism, the present study provides further methodological development focused on the elimination of bias that may occur during first-person observation. First, various sources of errors that may accompany introspection are distinguished based on previous critical literature. Four main errors are classified, namely attentional, attributional, conceptual, and expressional error. Furthermore, methodological recommendations for the possible elimination of these errors have been determined based on the analysis and focused excerpting of introspective scientific literature. The following groups of methodological recommendations were determined: 1) a better focusing of the subject’s attention to their mental processes, 2) providing suitable stimuli, and 3) the sharing of introspective experience between subjects. Furthermore, the potential of adjustments in introspective research designs for eliminating attentional, attributional, conceptual, and expressional error is discussed

    Approximate Decoding Approaches for Network Coded Correlated Data

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    This paper considers a framework where data from correlated sources are transmitted with help of network coding in ad-hoc network topologies. The correlated data are encoded independently at sensors and network coding is employed in the intermediate nodes in order to improve the data delivery performance. In such settings, we focus on the problem of reconstructing the sources at decoder when perfect decoding is not possible due to losses or bandwidth bottlenecks. We first show that the source data similarity can be used at decoder to permit decoding based on a novel and simple approximate decoding scheme. We analyze the influence of the network coding parameters and in particular the size of finite coding fields on the decoding performance. We further determine the optimal field size that maximizes the expected decoding performance as a trade-off between information loss incurred by limiting the resolution of the source data and the error probability in the reconstructed data. Moreover, we show that the performance of the approximate decoding improves when the accuracy of the source model increases even with simple approximate decoding techniques. We provide illustrative examples about the possible of our algorithms that can be deployed in sensor networks and distributed imaging applications. In both cases, the experimental results confirm the validity of our analysis and demonstrate the benefits of our low complexity solution for delivery of correlated data sources

    Contextual advantage for state discrimination

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    Finding quantitative aspects of quantum phenomena which cannot be explained by any classical model has foundational importance for understanding the boundary between classical and quantum theory. It also has practical significance for identifying information processing tasks for which those phenomena provide a quantum advantage. Using the framework of generalized noncontextuality as our notion of classicality, we find one such nonclassical feature within the phenomenology of quantum minimum error state discrimination. Namely, we identify quantitative limits on the success probability for minimum error state discrimination in any experiment described by a noncontextual ontological model. These constraints constitute noncontextuality inequalities that are violated by quantum theory, and this violation implies a quantum advantage for state discrimination relative to noncontextual models. Furthermore, our noncontextuality inequalities are robust to noise and are operationally formulated, so that any experimental violation of the inequalities is a witness of contextuality, independently of the validity of quantum theory. Along the way, we introduce new methods for analyzing noncontextuality scenarios, and demonstrate a tight connection between our minimum error state discrimination scenario and a Bell scenario.Comment: 18 pages, 9 figure

    Functional Bandits

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    We introduce the functional bandit problem, where the objective is to find an arm that optimises a known functional of the unknown arm-reward distributions. These problems arise in many settings such as maximum entropy methods in natural language processing, and risk-averse decision-making, but current best-arm identification techniques fail in these domains. We propose a new approach, that combines functional estimation and arm elimination, to tackle this problem. This method achieves provably efficient performance guarantees. In addition, we illustrate this method on a number of important functionals in risk management and information theory, and refine our generic theoretical results in those cases

    Hierarchical elimination-by-aspects and nested logit models of stated preferences for alternative fuel vehicles

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    1. INTRODUCTION Since the late 1960s, transport demand analysis has been the context for significant developments in model forms for the representation of discrete choice behaviour. Such developments have adhered almost exclusively to the behavioural paradigm of Random Utility Maximisation (RUM), first proposed by Marschak (1960) and Block and Marschak (1960). A common argument for the allegiance to RUM is that it ensures consistency with the fundamental axioms of microeconomic consumer theory and, it follows, permits interface between the demand model and the concepts of welfare economics (e.g. Koppelman and Wen, 2001). The desire to better represent observed choice, which has driven developments in RUM models, has been somewhat at odds, however, with the frequent assault on the utility maximisation paradigm, and by implication RUM, from a range of literatures. This critique has challenged the empirical validity of the fundamental axioms (e.g. Kahneman and Tversky, 2000; Mclntosh and Ryan, 2002; Saelensmide, 1999) and, more generally, the realism of the notion of instrumental rationality inherent in utility maximisation (e.g. Hargreaves-Heap, 1992; McFadden, 1999; Camerer, 1998). Emanating from these literatures has been an alternative family of so-called non-RUM models, which seek to offer greater realism in the representation of how individuals actually process choice tasks. The workshop on Methodological Developments at the 2000 Conference of the International Association for Travel Behaviour Research concluded: 'Non-RUM models deserve to be evaluated side-by-side with RUM models to determine their practicality, ability to describe behaviour, and usefulness for transportation policy. The research agenda should include tests of these models' (Bolduc and McFadden, 2001 p326). The present paper, together with a companion paper, Batley and Daly (2003), offer a timely contribution to this research priority. Batley and Daly (2003) present a detailed account of the theoretical derivation of RUM, and consider the relationships of two specific RUM forms; nested logit [NL] (Ben-Akiva, 1974; Williams, 1977; Daly and Zachary, 1976; McFadden, 1978) and recursive nested extreme value [RNEV] (Daly, 2001 ; Bierlaire, 2002; Daly and Bierlaire, 2003); to two specific non-RUM forms; elimination-by-aspects [EBA] (Tversky, 1972a, 1972b) and hierarchical EBA [HEBA] (Tversky and Sattath, 1979). In particular, Batley and Daly (2003) establish conditions under which NL and RNEV derive equivalent choice probabilities to HEBA and EBA, respectively. These findings would seem to ameliorate the concern that the application of RUM models to data generated by non-RUM choice processes could introduce significant biases. That aside, substantive issues remain as to how non-RUM models can best be specified so as to yield useful and robust information in both estimation and forecasting contexts, and how their empirical performance compares with RUM models. Such issues are the focus of the present paper, which applies non-RUM models to a real empirical context

    A heuristic model of bounded route choice in urban areas

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    There is substantial evidence to indicate that route choice in urban areas is complex cognitive process, conducted under uncertainty and formed on partial perspectives. Yet, conventional route choice models continue make simplistic assumptions around the nature of human cognitive ability, memory and preference. In this paper, a novel framework for route choice in urban areas is introduced, aiming to more accurately reflect the uncertain, bounded nature of route choice decision making. Two main advances are introduced. The first involves the definition of a hierarchical model of space representing the relationship between urban features and human cognition, combining findings from both the extensive previous literature on spatial cognition and a large route choice dataset. The second advance involves the development of heuristic rules for route choice decisions, building upon the hierarchical model of urban space. The heuristics describe the process by which quick, 'good enough' decisions are made when individuals are faced with uncertainty. This element of the model is once more constructed and parameterised according to findings from prior research and the trends identified within a large routing dataset. The paper outlines the implementation of the framework within a real-world context, validating the results against observed behaviours. Conclusions are offered as to the extension and improvement of this approach, outlining its potential as an alternative to other route choice modelling frameworks

    Factors Dictating Carbene Formation at (PNP)Ir

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    The mechanistic subtleties involved with the interaction of an amido/bis(phosphine)-supported (PNP)Ir fragment with a series of linear and cyclic ethers have been investigated using density functional theory. Our analysis has revealed the factors dictating reaction direction toward either an iridium-supported carbene or a vinyl ether adduct. The (PNP)Ir structure will allow carbene formation only from accessible carbons α to the ethereal oxygen, such that d electron back-donation from the metal to the carbene ligand is possible. Should these conditions be unavailable, the main competing pathway to form vinyl ether can occur, but only if the (PNP)Ir framework does not sterically interfere with the reacting ether. In situations where steric hindrance prevents unimpeded access to both pathways, the reaction may progress to the initial C−H activation but no further. Our mechanistic analysis is density functional independent and whenever possible confirmed experimentally by trapping intermediate species experimentally. We have also highlighted an interesting systematic error present in the DFT analysis of reactions where steric environment alters considerably within a reaction
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