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Results for “Uncertainty”

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PubMed1982

Input uncertainty and organizational coordination in hospital emergency units.

The relationships among input uncertainty, means of coordination, and criteria of the organizational effectiveness of hospital emergency units were explored using data from 30 emergency units in six midwestern states. Input uncertainty generally was not associated with the use of various means of coordination. However, input uncertainty affected relationships between the means of coordination and the effectiveness criteria. Specifically, programmed means of coordination made a greater contribution to organizational effectiveness under conditions of low uncertainty than under conditions of high uncertainty. Conversely, nonprogrammed means of coordination made a greater contribution to organizational effectiveness when uncertainty was high than when it was low. Findings were interpreted and suggestions were advanced as to how emergency units might best solve their coordination problems under varying conditions of uncertainty.

Efficiency↗

PubMed1999

Heart failure: living with uncertainty.

Uncertainty has been identified as a significant part of the experience of heart disease and yet no studies have fully explored the experience of uncertainty in persons living with chronic heart failure. The purpose of this study was to describe the uncertainty experienced by men and women with heart failure and to extend the theoretical understanding of uncertainty in chronic illness. Qualitative inquiry was the interpretive approach guiding this study. Data were collected from 22 adults living in urban and rural areas of a rural western state and included audio taped interviews, clinical and demographic information, and scores from the community form of the Mishel Uncertainty in illness Scale (MUIS-C). Three major themes of uncertainty were identified related to symptoms and treatment, attempts to stay well, and quality of life and death. Unique contributions to the uncertainty in illness theory provided by this study include the influence of age related changes on the ability to recognize and respond to symptoms and the presence of cautious trust of health care providers. Nursing implications and recommendations for further study are discussed.

Adaptation, Psychological↗

PubMed2001

Perceived social support, uncertainty, and quality of life of younger breast cancer survivors.

This study investigated the relationship between perceived social support, uncertainty, and quality of life among younger breast cancer survivors. Proposed hypotheses predicted a significant positive correlation between perceived social support and quality of life, a significant negative correlation between uncertainty and quality of life, and that perceived social support and uncertainty, considered together, will explain more of the variance of quality of life than either variable considered independently. A sample of 101 breast cancer survivors below age 50 completed the Social Support Questionnaire, Mishel Uncertainty in Illness Scale--Community Form, and Ferrans and Powers Quality of Life Index--Cancer Version. Data were analyzed using Pearson product-moment correlation and stepwise multiple regression. All three hypotheses were supported. Additional findings revealed a significant positive correlation between support and network size, and between network size and the socioeconomic domain of quality of life. Significant negative correlations were found between perceived social support and uncertainty, between network size and time since diagnosis and treatment, and between network size and uncertainty. Study results demonstrated that although perceived social support and uncertainty accounted for a significant amount (27.2%) of variance of quality of life, a large amount of variance remains unexplained. Further research is needed in this area.

Adult↗

PubMed2002

[The pediatrician, his laboratory and its uncertainty].

Four aspects of uncertainty linked to the laboratory of medical analysis are discussed. 1) Uncertainty and the laboratory test: the post-test probability of a diagnostic is intimately linked to the ability to establish clinically the pre-test probability. 2) Uncertainty and the patient: reference values are most often chosen from the literature. The analytical methodology as well as the population of reference should be carefully checked. 3) Uncertainty and the laboratory result: this uncertainty will diminish if preanalytical conditions are standardized and if analytical imprecision is known. The analytical imprecision is given by the coefficient of variation (CV) of the internal quality control. The CV is used to calculate the critical difference. 4) Uncertainty and the practitioner: to efficiently diminish this uncertainty in the case of unusual questions of the medical practice, a network should be established between the practitioner, the medical specialists and the scientific specialists of the laboratory.

Child↗

PubMedDate not supplied

Estimation of the measurement uncertainty of the high-performance anion-exchange chromatographic determination of carbohydrates in soluble (instant) coffee.

The measurement uncertainty of the determination of free and total carbohydrates in soluble (instant) coffee using high-performance anion exchange chromatography with pulsed amperometric detection according to AOAC Method 995.13 and ISO standard 11292 was calculated. This method is important with regard to monitoring several carbohydrate concentrations and is used to assess the authenticity of soluble coffee. We followed the recommendations of the ISO, Eurachem, and Valid Analytical Measurement (VAM) guides: individual uncertainty contributions u(x) were identified, quantified, and expressed as relative standard deviations related to each specific source u(x)/x or RSD(x). Eventually, they were combined to yield the standard uncertainty and the relative standard uncertainty of a given carbohydrate concentration, c, that is respectively u(c) and u(c)/c. As a result of our study, we could demonstrate that the overall repeatability of the carbohydrate determination in duplicate, RSD(r); the repeatability of the integration of the peak area of the carbohydrate standards, RSD(r(area)(ST)); and the uncertainty of the linear calibration model used in our laboratory, RSD (linST), are the most significant contributions to the total uncertainty. The u(c)/c values thus determined differ for each carbohydrate and depend on their concentrations. The least standard uncertainties that can be achieved are about 2.5%. The question of trueness in the total carbohydrate assay (determination of monosaccharides obtained upon hydrolysis of coffee oligo- and polysaccharides) was addressed. For this purpose, we analyzed the data of 2 different collaborative trials in which our laboratory took part.

Algorithms↗

PubMed1991

Reasoning in uncertainties. An analysis of five strategies and their suitability in pathology.

In reasoning systems, uncertainty plays a crucial part, especially for those fields in which judgements are essential, as in pathology. Uncertainty has several aspects, such as prevalence of diseases, occurrence of findings and the sensitivity and predictive value of findings. For the functioning of a reasoning system, two aspects are crucial: (1) the internal representation of the uncertainty and (2) the way in which the uncertainty is propagated in the reasoning process when combining formal statements. Five well-known reasoning strategies (Bayes' probability theory, MYCIN's certainty factor model, fuzzy set theory, the theory of Dempster-Shafer and Pathfinder's scoring mechanism) are compared, with particular attention to: (1) Under what conditions will the model function? In particular, what information is to be specified a priori to the system? (2) Can the different aspects of uncertainty be dealt with as separate entities? (3) How are unknown uncertainties dealt with? (4) How is evidence in favor of a hypothesis combined with evidence against it? (5) How does the model treat the simultaneous occurrence of more than one disorder, that is, how does the model support reasoning with compound hypotheses? It is preliminarily concluded that the different aspects of uncertainty are expressed as separate entities only in Pathfinder and probability theory. Hence, the other models do not accurately represent uncertain knowledge. Also, such theoretically attractive models as the Bayes, MYCIN and Dempster-Shafer theory can only function properly under the tight condition of mutual exclusiveness of hypotheses, which is not always suited for broader areas of pathology. They may, however, be suited for smaller areas, with a limited number of defined diseases and a limited number of features. All models but the Bayes model lack a predictable performance since there is no (or only a partial) underlying theory to guarantee minimization of the overall error.

Humans↗

PubMedDate not supplied

Finding meaning: antecedents of uncertainty in illness.

In this study a portion of the uncertainty in illness model was tested. Antecedents to uncertainty tested were the stimuli frame variables of symptom pattern and event familiarity and the structure provider variables of education, social support, and credible authority. Data were collected on a convenience sample of 61 women with gynecological cancer at the time of major treatment effect. Findings supported the proposed model with an empirically generated revised model presenting the influence of antecedents on specific areas of uncertainty. Divergent paths for reducing uncertainty were found. Social support, credible authority, and event familiarity had the greatest influence on lowering the level of uncertainty. Event familiarity and credible authority were primarily effective in reducing the complexity surrounding treatment and the system of care. Social support functioned to decrease the level of ambiguity concerning the state of the illness. Findings generally support the proposed explantation for uncertainty arousal and have substantive significance in identifying the sources of stimuli leading to uncertainty arousal and modification.

Adult↗

PubMed1979

The developmental relation between cognitive stage and the comprehension of speaker uncertainty.

3 hypotheses were tested concerning the developmental relation between children's concepts of physical uncertainty and their comprehension of a speaker's uncertainty. 2 cognitive tasks of physical uncertainty were used to assign 56 subjects (aged 5-4 to 17-11) to 1 of 3 cognitive stages. 2 tests for comprehension of speaker uncertainty were administered to all participants. The results indicated that cognitive stage was related to (a) comprehension that a speaker could be uncertain, (b) comprehension that uncertainty could be expressed in different degrees or magnitudes, and (c) the internal consistency of judgments made about the relative degree of uncertainty conveyed by an utterance. These findings are interpreted as evidence for the position that development of cognitive stages is structurally related to comprehension of speech act uncertainty.

Adolescent↗

PubMed1994

Uncertainty and quality of life of adults hospitalized with life-threatening ventricular arrhythmias.

Advances in the management of ventricular arrhythmias have improved patient survival, but not the uncertainty faced by those living with these arrhythmias. Managing the uncertainty in illness is considered essential to the maintenance of well-being and, therefore, quality of life. The purpose of this study was to determine the relationship between uncertainty and quality of life for adults with recurrent ventricular arrhythmias. Using a descriptive correlational design, 22 adults hospitalized with life-threatening ventricular arrhythmias completed questionnaires prior to discharge from the hospital. Data were collected using a demographic questionnaire, the Mishel Uncertainty in Illness Scale, the Quality of Life Index-Cardiac Version, and a single item self-rating scale for amount of worry. Results from the study indicated that greater quality of life for the health and functioning domain was significantly correlated with lower overall uncertainty and less ambiguity. Greater worry about the arrhythmia was associated with increased uncertainty and ambiguity, and poorer quality of life for the health and functioning domain. The results provide support for the aversive nature and negative impact of uncertainty on quality of life for patients with ventricular arrhythmias. Conclusions address clinical and research implications of these findings.

Adult↗

PubMed1997

Perceived uncertainty of outcome as a contributing factor in competitive state anxiety.

The Martens, Vealey, and Burton (1990) model of competitive anxiety contains perceived uncertainty, perceived importance, and competitive trait anxiety (A-trait) as key determinants affecting a person's perception of threat and competitive state anxiety (A-state). This experiment tested perceived uncertainty of outcome and A-trait influences on A-state. Club level golfers (N = 72) were assigned to either a low uncertainty condition (LU) or a high uncertainty (HU) condition. In this experiment participants were matched and competed for 12 golf balls in a modified chipping competition. Participants also completed the Competitive State Anxiety Inventory -2 and the Match Orientation Questionnaire (a measure of perceived uncertainty) prior to, and during breaks in the competition. Players alternated in taking four rounds of eight shots from a zone marked approximately 30 metres from the hole. A series of tests did not support the manipulation of uncertainty. This was probably due to likely losers and likely winners not experiencing similar levels of A-state, as Martens et al. assume. Recoding the uncertainty data to reflect levels of confidence, and entering confidence and A-trait into multiple regression equations resulted in these two variables accounting for between 15% and 23% of the A-state variance at different stages of the competition. Recommendations for future research, and possible revisions of the model in light of the present findings are discussed.

Adolescent↗

PubMed2006

Tolerance for uncertainty and perceived risk among women receiving uninformative BRCA1/2 test results.

Women who receive uninformative BRCA1/2 genetic test results face ongoing uncertainty about their future cancer risks. This article prospectively examined the influence of intolerance for uncertainty and perceived breast cancer risk on psychological distress following the receipt of uninformative BRCA1/2 test results. Sixty-four women who received uninformative BRCA1/2 mutation test results completed measures of Intolerance for Uncertainty, perceived breast cancer risk, and measures of cancer-related, genetic testing, and general distress. Cancer-related (DeltaR(2) = 0.18, P < or = 0.001), general (DeltaR(2) = 0.04, P < or = 0.05), and genetic testing distress (DeltaR(2) = 0.12, P < or = 0.01) were associated with intolerance for uncertainty at 1 month post-disclosure. The interaction of intolerance for uncertainty and breast cancer perceived risk predicted cancer-related (DeltaR(2) = 0.10, P < or = 0.001) and genetic testing distress (DeltaR(2) = 0.09, P < or = 0.01) at 6 months post-disclosure. Distress was highest among patients with highest perceived risk and intolerance for uncertainty, suggesting that those who have difficulty coping with their ambiguous risk are at risk for long-term distress. The clinical and research implications of these results are discussed.

Adult↗

PubMed2004

Feature uncertainty activates anterior cingulate cortex.

In visual discrimination tasks, the relevant feature to discriminate is defined before stimulus presentation. In feature uncertainty tasks, a cue about the relevant feature is provided after stimulus offset. We used (15)O-butanol positron emission tomography (PET) in order to investigate brain activation during a feature uncertainty task. There was greater activity during the feature uncertainty task, compared with stimulus detection and discrimination of orientation and spatial frequency, in the lateral and medial prefrontal cortex, the cuneus, superior temporal and inferior parietal cortex, cortical motor areas, and the cerebellum. The most robust and consistent activation was observed in the dorsal anterior cingulate cortex (Brodmann area 32; x = 0 y = 16, z = 40). The insula, located near the claustrum (x = -38, y = 8, z = 4), was activated during the discrimination tasks compared with the feature uncertainty condition. These results suggest that the dorsal anterior cingulate cortex is important in feature uncertainty conditions, which include divided attention, expectancy under uncertainty, and cognitive monitoring.

Adult↗

PubMed2005

Uncertainty in aflatoxin B1 analysis using information from proficiency tests.

We describe how to calculate uncertainty in the determination of aflatoxin B(1) in nuts and maize using an HPLC method with prederivatisation with trifluoroacetic acid and fluorescence detection. The uncertainty is easily calculated using the information obtained from the participation in several proficiency tests. All the sources of uncertainty are grouped in two terms: (1) matrix variability, intermediate precision and sample heterogeneity, and (2) method concordance. This methodology has the advantage that no extra work needs to be done because all the information to calculate uncertainty comes from proficiency tests. The uncertainty values were calculated using samples whose concentration ranged between 2 and 20 microg L(-1). The relative standard uncertainty computed for aflatoxin B(1) was 16.3%.

Aflatoxin B1↗

PubMed2005

Impact of geometric uncertainties on evaluation of treatment techniques for prostate cancer.

PURPOSE: To assess the impact of patient repositioning and internal organ motion on prostate treatment plans using three-dimensional conformal and intensity-modulated radiotherapy. METHODS AND MATERIALS: Four-field, six-field, and simplified intensity-modulated arc therapy plans were generated for 5 prostate cancer patients. The planning target volume was created by adding a 1-cm margin to the clinical target volume. A convolution model was used to estimate the effect of random geometric uncertainties during treatment. Dose statistics, tumor control probabilities, and normal tissue complication probabilities were compared with and without the presence of uncertainty. The impact of systematic uncertainties was also investigated. RESULTS: Compared with the planned treatments, the delivered dose distribution with random geometric uncertainties displayed an increase in the apparent minimal dose to the prostate and seminal vesicles and a decrease in the rectal volume receiving a high dose. This increased the tumor control probabilities and decreased the normal tissue complication probabilities. Changes were seen in the percentage of prostate volume receiving 100% and 95% of the prescribed dose, and the minimal dose and tumor control probabilities for the target volume. In addition, the volume receiving at least 65 Gy, the minimal dose, and normal tissue complication probabilities changed considerably for the rectum. The simplified intensity-modulated arc therapy technique was the most sensitive to systematic errors, especially in the anterior-posterior and superior-inferior directions. CONCLUSION: Geometric uncertainties should be considered when evaluating treatment plans. Contrary to the widely held belief, increased conformation of the dose distribution is not always associated with increased sensitivity to random geometric uncertainties if a sufficient planning target volume margin is used. Systematic errors may have a variable effect, depending on the treatment technique used.

Algorithms↗

PubMed2004

On the challenges of using evidence-based information: the role of clinical uncertainty.

Evidence-based medicine helps physicians appraise the latest and best evidence and incorporate patient's values in reaching a shared clinical decision. However, many decisions in medicine are made in the paucity of best evidence. Medical uncertainty remains inherent in clinical practice and contributes to significant variability in the way physicians and patients manage medical problems. Physicians and patients have varying degrees of tolerance for uncertainty. Intolerance to uncertainty among physicians results in increased test ordering tendencies, variability in medical treatment, failure to comply with evidence-based guidelines, and even guide career choices. Factors that result in the variability of physicians' interpretation of an effective treatment include: patient factors (prioritizing some factors over others), physician factors (lack of knowledge, lack of resources, medical uncertainty), and environmental factors (limitation of time and practice). Several approaches that have been found useful in implementing evidence in clinical practice include: sending reminders to prompt physicians to perform patient-related clinical activities, introducing computer information systems to support practice, and using interactive education interventions to teach newer skills and challenge negative attitudes. Passive educational approaches, like dissemination of guidelines and didactic lectures, are usually less useful in changing behavior. Among the techniques found to be useful for managing uncertainty are shared decision making, meticulous history taking, and physical examination, excluding worrisome differential diagnosis and establishing trust in patients. The role of future studies in assessing the outcome of multiple evidence-based strategies in situations of medical uncertainty remains to be explored.

Evidence-Based Medicine↗

PubMed2005

Uncertainty and information need in nursing.

The assumption of practitioner uncertainty as a cause of practice variation has focussed attention on the information behaviour of health care professionals, but there is very little research into clinical groups other than doctors. This study considered the information needs of nurses and their attributions for uncertainty. The method was participant observation of three groups of nurse specialists from multiple health care providers who met over time to construct evidence-based consensus recommendations for practice. Practitioners were uncertain about the best course of action in half of the issues discussed. There were clearly expressed areas of information need, but the workgroup process uncovered more implicit uncertainty than was expressed. The recognition of problems in practice was central to the articulation of information need, rather than the existence of new solutions. Of the known areas of uncertainty, only those that were problematic and had a visible, practical solution were followed up. Factors contributing to uncertainty included a perception of lack of evidence, and differences in how problems were presented in practice and research. The occurrence of unrecognised uncertainty suggests that there are areas of clinical practice where helping to recognise and articulate information need may stimulate further interest in evidence-based practice.

Anthropology, Cultural↗

PubMed2006

Young adult stimulant users' increased striatal activation during uncertainty is related to impulsivity.

BACKGROUND: Young adults who use stimulants (e.g., cocaine, amphetamines) are at particular risk of transitioning to dependence. Previously, we demonstrated increased risk-taking in young adults who had used stimulants (Leland, D.S., Paulus, M.P., 2005. Increased risk-taking decision-making but not altered response to punishment in stimulant-using young adults. Drug. Alcohol Depend. 78, 83-90). Since outcome uncertainty is a critical element of risk, we investigated whether such individuals have different neural responses to uncertainty than their stimulant-naive peers. METHOD: Eleven young adults (age 18-25) who had used stimulants were compared with 11 age- and education-matched stimulant-naive controls using functional magnetic resonance imaging and a card prediction task with relatively certain/uncertain outcome conditions. RESULTS: The caudate, an area involved in processing salient events, was among those regions more active in users than controls in response to uncertainty. Personality measures revealed that users were more impulsive than controls, and that neural response to uncertainty in a number of areas, including the thalamus/caudate, was positively correlated with impulsivity. CONCLUSIONS: These results are consistent with the idea that young adults who have used stimulants find uncertainty particularly salient, due in part to preexisting differences in impulsivity, and may be subject to more "action pressure" when making decisions under uncertainty. This neural and personality profile may constitute a marker for increased risk of stimulant use.

Adult↗

PubMed2005

Uncertainty, neuromodulation, and attention.

Uncertainty in various forms plagues our interactions with the environment. In a Bayesian statistical framework, optimal inference and prediction, based on unreliable observations in changing contexts, require the representation and manipulation of different forms of uncertainty. We propose that the neuromodulators acetylcholine and norepinephrine play a major role in the brain's implementation of these uncertainty computations. Acetylcholine signals expected uncertainty, coming from known unreliability of predictive cues within a context. Norepinephrine signals unexpected uncertainty, as when unsignaled context switches produce strongly unexpected observations. These uncertainty signals interact to enable optimal inference and learning in noisy and changeable environments. This formulation is consistent with a wealth of physiological, pharmacological, and behavioral data implicating acetylcholine and norepinephrine in specific aspects of a range of cognitive processes. Moreover, the model suggests a class of attentional cueing tasks that involve both neuromodulators and shows how their interactions may be part-antagonistic, part-synergistic.

Acetylcholine↗