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Results for “Utility Theory”

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PubMed2002

Intramuscular sensation in conscious human subjects: a qualitative and quantitative study utilizing signal detection theory methodology.

To investigate whether human subjects could consciously perceive different levels of intramuscular sensation, EMG needle electrodes were inserted into the forearm extensor musculature. Qualitative descriptions of the types of sensations evoked at various current intensities were recorded. A series of preliminary experiments was performed in order to determine the optimum waveform, current intensity, duration and separation between adjacent current pairs that could reliably be discriminated by conscious human subjects. The methodology of signal detection theory was utilized to obtain the discrimination measure, d' (d prime). Values of d' were obtained for sequential blocks of trials consisting of randomly delivered blocks of 50 "strong" and 50 "weak" stimuli. The ability to discriminate both noxious and non-noxious stimuli was determined using d'. It was demonstrated that human subjects are able to qualitatively describe non-nociceptive sensations elicited by low levels of intramuscular stimulation. Subjects were able to reliably discriminate pairs of electrical stimuli separated in intensity by 0.4 dB over four sequential blocks of trials on the same day and on different days. This work demonstrates that signal detection theory methods can reliably measure sensory discrimination in skeletal muscle, for both noxious and non-noxious levels of electrical stimulation. A protocol is proposed for appropriate future use of this methodology to investigate alterations in muscle sensation following experimental interventions.

Adult↗
PubMed2006

Behavioral theories and the neurophysiology of reward.

The functions of rewards are based primarily on their effects on behavior and are less directly governed by the physics and chemistry of input events as in sensory systems. Therefore, the investigation of neural mechanisms underlying reward functions requires behavioral theories that can conceptualize the different effects of rewards on behavior. The scientific investigation of behavioral processes by animal learning theory and economic utility theory has produced a theoretical framework that can help to elucidate the neural correlates for reward functions in learning, goal-directed approach behavior, and decision making under uncertainty. Individual neurons can be studied in the reward systems of the brain, including dopamine neurons, orbitofrontal cortex, and striatum. The neural activity can be related to basic theoretical terms of reward and uncertainty, such as contiguity, contingency, prediction error, magnitude, probability, expected value, and variance.

Animals↗
PubMed1984

Multiattribute decision analysis of clinical errors: a case study of computerized arrhythmia detectors.

Two types of errors are observed in the process of medical decision making: false positives and false negatives. For various detection criteria these errors are usually plotted to form detection curves. The problem of identifying optimum detection criteria that minimize the impact of these errors is addressed. Usually this involves trade-offs that are determined by the attitudes of the medical decision maker, types of disease, and clinical settings. Utility theory is the theoretical technique developed to quantify subjective elements of decision making. Techniques of utility theory were employed to experimentally obtained data on errors committed by an automated arrhythmia monitor. Two cardiologists were interviewed to assess their utility functions and a multiattribute decision-analysis technique was used. From the utility functions the best detection criteria for the automated arrhythmia detector were determined. This research also highlights various behaviors in medical setting: risk neutral, risk averse , and risk seeking. The effects of various diseases and clinical settings on decision making were also shown.

Arrhythmias, Cardiac↗
PubMed1995

[QALYS or not QALYS: that is the question?].

The article discusses the proposal of some health economists to use the "cost per QALY (quality-adjusted-life year)" ratio as an universal indicator for economic assessment of medical interventions, in the so-called "cost-utility" analyses. Authors argue that QALYs are not a straightforward application of expected utility theory, which is the standard economic model of individual behaviours toward risk and uncertainty. Indeed, QALYs are compatible with economic utility theory only if individuals' preferences regarding health states satisfy certain very restrictive properties: utility independence between length of life and quality of life, constancy of the proportional trade-off between quality of life and length of life, risk neutrality towards health states, constancy through time of the utility associated with each health state. Aggregation of individual QALYs to obtain an indicator for patient groups at the societal level also raises complex equity problems. Last but not least, from the epistemological point of view, QALYs are based on the hypothesis that health interventions only affect the health of the individual and not any other aspects of his well-being. The authors conclude that the "cost per QALY" approach should be abandoned in order to avoid ambiguities that could impede the development of health economics in the medical field.

Choice Behavior↗
PubMed2005

Theory and utility--key themes in evidence-based assessment: comment on the special section.

This article focuses on two key themes in the four featured reviews on evidence-based assessment. The first theme is the essential role of theory in psychological assessment. An overview of this complex, multilayered role is presented. The second theme is the need for a common metric with which to gauge the utility of specific psychological tests and measures for specific purposes. A metric from information theory is recommended. The implications of these themes for the four reviews and for the future of psychological assessment in general are discussed.

Evidence-Based Medicine↗
PubMed1993

Objective evaluation of radiation treatment plans.

The evaluation of radiation treatment plans involves making trade-offs among doses delivered to the tumor volumes and nearby normal tissues. Evaluating state-of-the-art three-dimensional (3D) plans is a difficult task because of the huge amount of planning data that needs to be deciphered. Multiattribute utility theory provides a methodology for specifying trade-offs and selecting the optimal plan from many competing plans. Using multiattribute utility theory, we are developing a clinically meaningful objective plan-evaluation model for 3D radiation treatment plans. Our model incorporates three of the factors involved in radiation treatment evaluation--treatment preferences of the radiation oncologist, clinical condition of the patient, and complexity of the treatment plan.

Decision Support Techniques↗
PubMed2005

Predictors of multivitamin supplement use among African-American female students: a prospective study utilizing the theory of planned behavior.

BACKGROUND: Public health officials recommend that women capable of becoming pregnant use folic acid-containing supplements (FAS) to prevent neural tube defects (NTD) in their newborn infants. However, the knowledge about NTD prevention and the prevalence of the use of FAS among women capable of becoming pregnant increased only modestly since the issuing of the recommendation in 1992. Since most commonly available multivitamin supplements (MVS) contain the recommended 400 gg of folic acid, finding out reasons why women take MVS and utilizing these factors in educational campaigns may contribute to increasing the use of FAS. METHODS: The Theory of Planned Behavior variables and the self-reported use of MVS were measured by two separate surveys within one week. A preliminary open-ended questionnaire was utilized to elicit beliefs about MVS. A convenience sample of 100 African-American female college students, mean age 20.99 (SD=1.7) years, participated in this study. RESULTS: Approximately 65% of variance in behavioral intention was explained by attitude, subjective norms, and perceived behavioral control (P<.001). Subjective norms had the greatest influence (3=0.348, P<.001), followed by PBC (3=0.336, P<.001), and attitude (1=0.228, P<.038). Behavioral intention significantly predicted the use of MVS accounting for =59.2% of variance. CONCLUSION: Consistent with the results of the present study, educational campaigns that target African-American female college students to encourage the use of MVS should focus on the impact of physicians, family, and peers.

Adult↗
PubMed1986

Hospice program development: the nurse as a change agent.

A theory is an explanation of the interrelation among facts, concepts, or propositions. A number of theories are used in the process of hospice program assessment, including nursing process, change systems, and role theory. Collaboration between systems is crucial to the development of a smooth-running, effective hospital-community network. As a result of the theories utilized, the tools and skills needed to effect change, the driving and restraining forces that need to be identified, and the need to focus on a specific goal have been described. Although the theories utilized in this hospice study will not predict the outcome of the project, they have provided us with structure that enables us to guide our action and organize our approach to program analysis.

Hospices↗
PubMed2004

Risk-adjusted mission value: trading off mission risk for mission value.

This article develops a decision-theoretic methodology for the risk-adjusted mission value (RAMV) for selecting between alternative missions in the presence of uncertainty in the outcomes of the missions. This methodology permits trading off mission risk for mission value, something that probabilistic risk analysis cannot do unless it explicitly incorporates both mission value and risk aversion of the project management. The methodology, in its complete implementation, is consistent with the decision theory known as expected utility theory, although it differs from conventional decision theory in that the probabilities and all but one of the utilities are not those of the decision maker. The article also introduces a new interpretation of risk aversion. The methodology is consistent with the elementary management concept concerning division of labor. An example is presented for selecting between discrete alternatives-four landing sites on Mars. A second example is presented for selecting among a set of continuous alternatives-a comet flyby distance. The methodology is developed within the context of scientific missions, but the methodology is equally applicable to any situation requiring outcome value judgments, probability judgments, and risk aversion judgments by different constituencies.

Journal Article↗
PubMedDate not supplied

Decision analysis with cumulative prospect theory.

BACKGROUND: Individuals sometimes express preferences that do not follow expected utility theory. Cumulative prospect theory adjusts for some phenomena by using decision weights rather than probabilities when analyzing a decision tree. METHODS: The authors examined how probability transformations from cumulative prospect theory might alter a decision analysis of a prophylactic therapy in AIDS, eliciting utilities from patients with HIV infection (n = 75) and calculating expected outcomes using an established Markov model. They next focused on transformations of three sets of probabilities: 1) the probabilities used in calculating standard-gamble utility scores; 2) the probabilities of being in discrete Markov states; 3) the probabilities of transitioning between Markov states. RESULTS: The same prophylaxis strategy yielded the highest quality-adjusted survival under all transformations. For the average patient, prophylaxis appeared relatively less advantageous when standard-gamble utilities were transformed. Prophylaxis appeared relatively more advantageous when state probabilities were transformed and relatively less advantageous when transition probabilities were transformed. Transforming standard-gamble and transition probabilities simultaneously decreased the gain from prophylaxis by almost half. Sensitivity analysis indicated that even near-linear probability weighting transformations could substantially alter quality-adjusted survival estimates. CONCLUSION: The magnitude of benefit estimated in a decision-analytic model can change significantly after using cumulative prospect theory. Incorporating cumulative prospect theory into decision analysis can provide a form of sensitivity analysis and may help describe when people deviate from expected utility theory.

AIDS-Related Opportunistic Infections↗
PubMed2002

Framing effects and risky decisions in starlings.

Animals are predominantly risk prone toward reward delays and risk averse toward reward amounts. Humans in turn tend to be risk-seeking for losses and risk averse for gains. To explain the human results, Prospect Theory postulates a convex utility for losses and concave utility for gains. In contrast, Scalar Utility Theory (SUT) explains the animal data by postulating that the cognitive representation of outcomes follows Weber's Law, namely that the spread of the distribution of expected outcomes is proportional to its mean. SUT also would explain human results if utility (even if it is linear on expected outcome) followed Weber's Law. We present an experiment that simulates losses and gains in a bird, the European Starling, to test the implication of SUT that risk proneness/aversion should extend to any aversive/desirable dimension other than time and amount of reward. Losses and gains were simulated by offering choices of fixed vs. variable outcomes with lower or higher outcomes than what the birds expected. The subjects were significantly more risk prone for losses than for gains but, against expectations, they were not significantly risk averse toward gains. The results are thus, in part, consistent with Prospect Theory and SUT and show that risk attitude in humans and birds may obey a common fundamental principle.

Animals↗
PubMed1989

QALYs: are they enough? A health economist's perspective.

John Rawles's criticism of QALYs are seen as being both imprecise and largely unhelpful. This paper accepts that there are problems in both QALYs themselves and in the current decision-making processes with which they seek to help. The QALY pliers tend to play down the former and the QALY knockers the latter. It is suggested that theories (regret theory and prospect theory) other than expected utility theory, which is normally seen as the basis for QALYs, may provide better approaches to measuring health service outputs. Thus equity, information and decision-making per se are not handled as well in the expected utility QALYs as they could be. Developing better QALYs, with qualifications, is the goal.

Decision Making↗
PubMed1999

The Effects of Framing, Reflection, Probability, and Payoff on Risk Preference in Choice Tasks.

A meta-analysis of Asian-disease-like studies is presented to identify the factors which determine risk preference. First the confoundings between probability levels, payoffs, and framing conditions are clarified in a task analysis. Then the role of framing, reflection, probability, type, and size of payoff is evaluated in a meta-analysis. It is shown that bidirectional framing effects exist for gains and for losses. Presenting outcomes as gains tends to induce risk aversion, while presenting outcomes as losses tends to induce risk seeking. Risk preference is also shown to depend on the size of the payoffs, on the probability levels, and on the type of good at stake (money/property vs human lives). In general, higher payoffs lead to increasing risk aversion. Higher probabilities lead to increasing risk aversion for gains and to increasing risk seeking for losses. These findings are confirmed by a subsequent empirical test. Shortcomings of existing formal theories, such as prospect theory, cumulative prospect theory, venture theory, and Markowitz's utility theory, are identified. It is shown that it is not probabilities or payoffs, but the framing condition, which explains most variance. These findings are interpreted as showing that no linear combination of formally relevant predictors is sufficient to capture the essence of the framing phenomenon. Copyright 1999 Academic Press.

Journal Article↗
PubMed1993

Airflow measurements: theory and utility of findings.

The biomechanical movements of vocal structures are shown to control flow of expiratory air for the production of speech sounds. Laminar and turbulent air flow are discussed as they relate to sound generation. Theoretic and therapeutic utility of air flow profiles in differentiating linguistic contrasts and vocal characteristics are discussed along with considerations of relative utility and accuracy for various flow-measuring devices and strategies.

Adolescent↗
PubMed1993

Testing four competing theories of health-protective behavior.

Four competing theories of health-protective behavior are reviewed: the health belief model, the theory of reasoned action, protection motivation theory, and subjective expected utility theory. In spite of their commonalities, these models are seldom tested against one another. The review points out the similarities and differences among these theories and the data and analyses needed to compare them. In addition to describing the content of the models, their conceptualization of key variables, and the combinatorial rules used to make predictions, some general problems in theory development and testing for health behaviors are examined. The article's goal is to help investigators design studies that will clarify the strengths and weaknesses of these models, leading toward a better understanding of health behavior.

Attitude to Health↗