Uncertainty in economic decision-making can present itself in a variety of forms however the most commonly researched are risk and ambiguity. Recently, there has been a resurgence of interest in evaluating the relationship between individuals’ preference for risk and ambiguity through the use of cognitive decision models. Accurately characterizing these preferences therefore relies on the use of appropriate models and model fitting techniques. Huettel, Stowe, Gordon, Warner & Platt (2006) used Expected Utility Theory (EUT) and the alpha maxmin model to evaluate individuals risk and ambiguity preference, respectively. Their results suggest that risk and ambiguity evoke disparate cognitive processes at both a behavioural and neural level. However, the use of EUT in characterizing risk preference calls into question the accuracy of their results. The present study attempts to re-evaluate the relationship between risk and ambiguity using a more appropriate and well-established model of risky decision-making, Cumulative Prospect Theory (CPT). Using a similar task design as Huettel et al. (2006), participants (N = 93) were required to make a series of decisions between two options that involved monetary outcomes. Each trial consisted of choices between two of the following options: risky, certain and ambiguous. Parameters for both EUT and CPT were estimated on risky trials and used to inform the estimation of ambiguity parameters using the α-maxmin on ambiguous trials. Moreover, each model was estimated using two methods of model fitting, optimization and hierarchical Bayesian analysis methods. Overall, CPT outperformed EUT on risky trials as well, ambiguity parameters from α-maxmin informed by CPT risk parameters outperformed EUT informed α-maxmin parameters. Finally, CPT estimated alpha and beta values were found to be uncorrelated. However, the present results demonstrate that ambiguity preference parameters correlate with the probability distortion parameters that may be a more accurate depiction of an individuals’ level of risk preference. These results can be used to inform future endeavours uncovering the neural correlates of levels of uncertainty in decision-making. / Graduate

This thesis is concerned with determining the orientation of small Unmanned Aerial Vehicles(UAVs). To make commercial use of these aircraft in aerial surveying markets their attitude needs to be determined accurately and precisely throughout a survey flight. Traditionally inertial sensors have been used on larger aircraft to estimate both position and orientation in combination with Global Navigation Satellite Systems (GNSS). High quality inertial sensors have many downsides when used on the small UAV. They are expensive, power hungry and often heavy. Inertial sensors are vulnerable to vibration, high acceleration, high rotation rate and jerk. All of these are present on the small UAV. This thesis identifies GNSS attitude determination as a potentially suitable alternative to inertial techniques. Carrier phase GNSS attitude determination uses three or more GNSS receivers with antennas separated by a short baseline to estimate the orientation of the UAV. This technique offers low cost, high accuracy and drift-free attitude estimates. To be successfully used it requires removal of the biases present in the received GNSS signals and estimation of the integer cycle ambiguity present in the carrier phase measurement. This thesis presents and examines the state of the art techniques for removing these biases and estimating an integer cycle ambiguity using a priori measurement of the interantenna distance. In this work a novel method is developed which uses this a priori baseline measurement to validate estimates of the carrier phase ambiguities. In order to test these methods data has been gathered using low cost, commercially available GNSS receivers and antennas. This is the first work in which modern, low cost, GNSS equipment has been tested for use in attitude determination. It is found that the state of the art carrier phase GNSS attitude determination methods can provide an accurate attitude estimate for every set of measurements from the GNSS receivers. However, a real UAV flight indicates that the low cost GNSS equipment does not track the GNSS signals throughout the flight. Signal outages, cycle slips and half cycle ambiguous carrier phase measurements occur due to rapid UAV manoeuvres. Having identified this problem this work goes on to replicate and quantify it through the use of a GNSS hardware simulator. Algorithms are then devised to increase the availability of the GNSS attitude solution throughout the tracking difficulties. Complete GNSS signal tracking failures are overcome through the innovative use of kinematic and dynamic attitude models. Both types of model give an attitude solution throughout GNSS signal tracking problems without adding significant cost or weight to the system. When tracking of the GNSS carrier phase signal is possible, novel use of the carrier phase triple difference observable allows the attitude rate to be estimated even when the carrier phase measurements are half cycle ambiguous. It is shown that integer and half integer cycle slips can be removed from the measurement through the combination of the modelling and triple difference techniques. The attitude output of both modelling and triple difference methods is used to resolve half cycle ambiguities and make full use of half cycle ambiguous data where previously it could not have been used. Success rates of up to 99.6% have been achieved for half cycle ambiguity resolution. As a result precise and accurate GNSS attitude solutions are available at nearly every epoch for which a carrier phase measurement is output by the GNSS receivers. When no measurement is available the attitude solution gracefully degrades over time. This work makes reliable, accurate, low cost attitude determination possible on mini-UAVs.

This project looks half a century in the past to begin making sense of how and why the obese child has become visible as a significant public problem in the United States. The central argument of this dissertation is that the development of physical education as a discipline and its articulation to the physical fitness panic of the 1950s functioned rhetorically by framing physical fitness as a category necessary for performing one's citizenship. Indeed, I argue that the articulation of the fit body to American citizenship is a crucial component in the emergence of the obese child as a public problem. By examining the interrelated themes of physical education, public problems, materialist rhetoric, ambiguity, and history, I demonstrate that rhetorical practices not only function as mechanisms for disciplining the practices of citizens, but also create opportunities for re-imagining the body and its value in society. In chapter two, I address these themes through an historicization of the disciplinary development of physical education as it changed over time. Chapter three explores the ways in which McCarthyism and increased instances of juvenile delinquency in the 1950s cultivated a politico-cultural environment that necessitated a method capable of managing the behavior of deviant individuals. This need for the management of deviance along with developments in physical education contributed to the emergence of the President's Council on Youth Fitness, an institution that drew national attention to the importance of physical fitness. Finally, chapter four examines the circulation of the ways in which physical fitness' status as a public problem was made possible by the ambiguous nature of the term fitness. In making visible the contingent nature of the fitness problem, its implications, and the means by which it operates, this study provides a starting point through which alternatives for current understandings of the body and its value can be conceived. The specific route through which such a re-conceptualization of the body could occur is found within moments where the persuasive force of language leaves room for (mis)interpretation, the liminal space created through rhetorical ambiguity.

The importance of attribute vector ambiguity has been largely overlooked by the machine learning community. A pattern recognition problem can be solved in many ways within the scope of machine learning. Neural Networks, Decision Tree Algorithms such as C4.5, Bayesian Classifiers, and Instance Based Learning are the main algorithms. All listed solutions fail to address ambiguity in the attribute vector. The research reported shows, ignoring this ambiguity leads to problems of classifier scalability and issues with instance collection and aggregation. The Algorithm presented accounts for both ambiguity of the attribute vector and class label thus solving both issues of scalability and instance collection. The research also shows that when applied to sanitized data sets, suitable for traditional instance based learning, the presented algorithm performs equally as well.

The use of masks in performance and actor training is often linked to the imagination, but there is seldom discussion of the nature of this imaginary link. Using the philosophy of Jean-Paul Sartre (most especially his work The Imaginary) and the writings of modern mask theorists, this dissertation examines the relationship between masks and the imaging consciousness in both masked actors and the audiences who observe them. We discover that a mask is an analogon for an Other and that a mask authorizes games of identity which play out imaginatively in the performance milieu. In fact, generally speaking, a mask in performance is apprehended in a more imaginative way than a non-masked performance. Further than this, the mask illustrates the basic nature of the human consciousness and identity espoused by Sartre: that who we are is not a product of our psychology, but rather, the product of our imaginations and our choices. The dissertation concludes by suggesting that masks point to an alternative approach to character creation which likewise rejects psychology, and instead relies on physicality, abstraction, and ambiguity, all of which are essential to activating the imaging consciousness.

Esta tesis es dividida en tres capítulos que se refieren a dos temas diferentes. El segundo capítulo se concentra en los efectos incentivos de bajar salarios llanos y su papel en la ayuda del fracaso de coordinación vencido. Los resultados débilmente apoyan los efectos positivos de bajar salarios llanos. Los dos papeles en los terceros y cuartos capítulos relacionan los estudios de la incertidumbre de información de riesgo y ambigüedad en juegos de entrada de mercado. Estudiamos experimentalmente decisiones bajo la incertidumbre de riesgo y ambigüedad en juegos de entrada de mercado, que captura los rasgos básicos de los fenómenos sobre la entrada en el mercado. La tarea importante es averiguar si la participación excesiva está relacionada con los tipos de información de riesgo y ambigüedad, y si las decisiones son diferentes en riesgo y ambigüedad en ambientes estratégicos. Encontramos la ambigüedad que busca en un ajuste de mercado de un ambiente relativo del mercado de información arriesgado y ambiguo en la correspondencia fija. Sin embargo, en un ambiente no relativo del mercado de información arriesgado y ambiguo, la busca de ambigüedad es saliente en la correspondencia arbitraria, pero no en la correspondencia fija. Encontramos que los efectos de ambigüedad en juegos estratégicos no dependen de si el riesgo y la ambigüedad son puestos en contextos relativos o no relativos, pero en la complejidad estratégica en los juegos. Más fuerte la complejidad estratégica es, más saliente la ambigüedad efectúa. / This thesis is divided into three chapters that refer to two different topics. The second chapter focuses on the incentive effects of lowering flat wages and its role in helping overcome coordination failure. The results weakly support the positive effects of lowering flat wages. The two papers in the third and fourth chapters relate the studies of information uncertainty of risk and ambiguity in market entry games. We study experimentally decisions under uncertainty of risk and ambiguity in market entry games, which captures the basic features of the phenomena over entry in the market. The important task is to find out whether the excessive participation is related to the information types of risk and ambiguity, and whether decisions are different in risk and ambiguity in strategic environments. We find ambiguity seeking in a market setting of a comparative environment of risky and ambiguous information market in fixed matching. However, in a non-comparative environment of risky and ambiguous information market, ambiguity seeking is salient in random matching, but not in fixed matching. We find that ambiguity effects in strategic games do not depend on whether risk and ambiguity are put in comparative or non-comparative contexts, but on the strategic complexity in the games. The stronger the strategic complexity is, the more salient the ambiguity effects.

Detecting ambiguity is essential for successful communication. Two studies investigated whether preschool- (4- to 5-year-old) and school-age (6- to 7-year-old) children show sensitivity to communicative ambiguity and can use this cue to determine which speakers constitute valuable informational sources. Children were provided clues to the location of hidden dots by speakers who varied in clarity and accuracy. Subsequently, children decided from whom they would like to receive additional information. In Study 1, preschool- (n=40) and school-age (n=42) children preferred to solicit information from unambiguous than from ambiguous speakers. However, ambiguous speakers were preferred to speakers who provided inaccurate information. In Study 2, when not provided with information about the outcome of the speakers’ clues, school-age (n=22), but not preschool-age (n=19), children preferred unambiguous relative to ambiguous speakers. Results highlight a developmental progression in children’s use of communicative ambiguity as a cue to determining which individuals are preferable informants.

An outcome is ambiguous if it is an incomplete description of the probability distribution over consequences. An `incomplete description' is identified with the set of probabilities that satisfy the incomplete description. A choice problem is uncertain if the decision maker is choosing between distributions, and is ambiguous if the decision maker is choosing between sets of probabilities. The von Neumann/Morgenstern approach to uncertain choice problems uses a continuous linear function on probabilities. This paper develops the theory of ambiguous choice problems as a continuous, linear functions on closed convex sets of probabilities. This delivers: a framework encompassing most of the extant ambiguity averse preferences; a complete separation of attitudes towards risk and attitudes toward ambiguity; and generalizations of rst and second order stochastic dominance rankings to ambiguous decision problem. Quasi-concave preferences on sets that satisfy a restricted betweenness property capture variational preferences. / text

This dissertation consists of three economic experiments that investigate behavioral differences in decision making process under risk (uncertainty with known probabilities) and under ambiguity (uncertainty with unknown probabilities). The first and the second chapters present two experiments with subjects choosing between lotteries involving risky and ambiguous urns. Decisions are made in conjunction with a sequence of random draws with replacement, allowing us to track the beliefs of the agents at different moments in time. In the first chapter, we develop and estimate a model of subjective belief updating allowing for base rate fallacy. We find that when updating under ambiguity subjects significantly underweight the new signal, while when updating under compound risk subjects are essentially Bayesian. In the second chapter, we estimate a popular multiple priors model for decision making under ambiguity in dynamic environments. Our estimates suggest a difference in the confidence with which subjects discard the unlikely priors depending on whether an ambiguous urn was presented first or second. Specifically, when an ambiguous urn is presented first, subjects consider more priors during the learning process as compared to when a compound urn is presented first. We also find significant evidence against the hypothesis that human subjects consider only Dirac priors. In the third chapter, we examine the behavior of security dealers in an environment where the level of asymmetric information is viewed as either risk, compound risk, or ambiguity. Using two measures of market liquidity, resiliency and price, we find that duopoly dealer markets are both more resilient to uncertainty about asymmetric information as well as having higher dealer bids compared with monopoly dealer markets for all three uncertainty scenarios. Additionally, we find differences in dealer bidding behavior in duopoly setting depending on whether the uncertainty about informed trading is presented as risk, compound risk, or ambiguity. / text

A growing number of studies suggest that accounting information risk, primarily idiosyncratic in nature, can be diversified away in the capital market. In this dissertation, I show that accounting information risk, proxied by accruals quality, is priced even if it is entirely idiosyncratic. In particular, building on a model from the ambiguity literature, I demonstrate that (1) in an under-diversified market, idiosyncratic information risk is priced even if it is diversifiable, and (2) in a well-diversified market, idiosyncratic information risk is priced when information is subject to managers' discretion and thus ambiguous. The empirical results corroborate the predictions from the model. Specifically, although an association is observed between (unambiguous if risky) innate accruals quality and cost of capital, the association can be largely mitigated through diversification. However, diversification has little impact on the association between (ambiguous) discretionary accruals quality and cost of capital. Taken together, these findings strengthen our understanding of the fundamental role of accounting information as a basis for capital allocation.