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Results for “Uncertainty”

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PubMed2005

Uncertainty management intervention for older African American and caucasian long-term breast cancer survivors.

The survivor uncertainty management intervention study is a randomized controlled study designed to test the efficacy of an intervention that combines training in audiotaped cognitive behavioral strategies to manage uncertainty about cancer recurrence with a self-help manual designed to help women understand and manage long-term treatment side effects and other symptoms. Specifically, women were taught to recognize their own personal triggers of uncertainty (places, events or surroundings, that bring back memories, feelings, or concerns about breast cancer), and then use coping skills such as relaxation, distraction, and calming self-talk to deal with uncertainty. Also, women were taught to use the manual as a resource for dealing with fatigue, lymphedema, pain and other symptoms. Treatment outcome data (Mishel et al., in press) indicated that the uncertainty management intervention resulted in improvements in cognitive reframing, cancer knowledge, social support, knowledge of symptoms and side effects, and coping skills when compared to a control condition. The purpose of the present paper was to report on the use and helpfulness of the intervention components by the 244 women who were in the intervention. Findings indicated that women regularly used the intervention components to deal with triggers of breast cancer recurrence and long-term treatment side effects and most women found the strategies very helpful.

Adult↗

PubMed2001

A 100 years of certitude? Social psychology, the experimental method and the management of scientific uncertainty.

For at least 100 years the experimental method has been used to add scientific rigour to the process of conducting social psychological research. More specifically, experiments have been used to reduce methodological uncertainty surrounding the causal relationships between variables. In this way the method has proved particularly useful in demonstrating the impact of social contextual variables over-and-above individual differences. However, problems with the method have arisen because over time experimentalists have tended (1) to define uncertainty too narrowly, (2) to emphasize uncertainty reduction, but (3) to neglect the equally important process of uncertainty creation. This has contributed to the normalization of social psychology as a science but also made the discipline more conservative and circumscribed. It is argued that experimentalists need to address broader metatheoretical and political uncertainties in order to rediscover the experiment's potency as a tool of revolutionary and progressive science.

Epidemiologic Methods↗

PubMed2005

Uncertainty analysis of displacements measured by in-plane electronic speckle-pattern interferometry with spherical wave fronts.

Displacement measurements by optical interferometry depend on the induced phase difference and on the interferometer's sensitivity vector; the latter depends in turn on the illuminating sources and on the geometry of the optical arrangement. We have performed an uncertainty analysis of the in-plane displacements measured by electronic speckle-pattern interferometry with spherical incident wave fronts. We induced the displacements by applying a uniaxial tensile load on a nominally flat elastic sample. We approached the displacement uncertainty by propagating the uncertainties that we considered reasonable to assign to the measured phase difference and to the characteristic parameters of the interferometer's sensitivity vector. Special attention was paid to evaluating contributions to the displacement uncertainty. Moreover, we observed that the uncertainty decreases if the angles of incidence and the source-target distances are increased.

Journal Article↗

PubMed2006

Some statistical implications of dose uncertainty in radiation dose-response analyses.

Statistical dose-response analyses in radiation epidemiology can produce misleading results if they fail to account for radiation dose uncertainties. While dosimetries may differ substantially depending on the ways in which the subjects were exposed, the statistical problems typically involve a predominantly linear dose-response curve, multiple sources of uncertainty, and uncertainty magnitudes that are best characterized as proportional rather than additive. We discuss some basic statistical issues in this setting, including the bias and shape distortion induced by classical and Berkson uncertainties, the effect of uncertain dose-prediction model parameters on estimated dose-response curves, and some notes on statistical methods for dose-response estimation in the presence of radiation dose uncertainties.

Artifacts↗

PubMed2006

Childhood thyroid cancer, radiation dose from Chernobyl, and dose uncertainties in Bryansk Oblast, Russia: a population-based case-control study.

A population-based case-control study was conducted to estimate the radiation-related risk of thyroid cancer in persons who were exposed in childhood to (131)I from the Chernobyl accident of April 26, 1986 and to investigate the impact of uncertainties in individual dose estimates. Included were all 66 confirmed cases of primary thyroid cancer diagnosed from April 26, 1986 through September 1998 in residents of Bryansk Oblast, Russia, who were 0-19 years old at the time of the accident, along with two individually matched controls for each case. Thyroid radiation doses, estimated using a semi-empirical model based on environmental contamination data and individual characteristics, ranged from 0.00014 Gy to 2.73 Gy and had large uncertainties (median geometric standard deviation 2.2). The estimated excess relative risk (ERR) associated with radiation exposure, 48.7/Gy, was significantly greater than 0 (P = 0.00013) but had an extremely wide 95% confidence interval (4.8 to 1151/Gy). Adjusting for dose uncertainty nearly tripled the ERR to 138/Gy, although this was likely an overestimate due to limitations in the modeling of dose uncertainties. The radiation-related excess risk observed in this study is quite large, especially if the uncertainty of dose estimation is taken into account, but is not inconsistent with estimates previously reported for risk after (131)I exposure or acute irradiation from external sources.

Adolescent↗

PubMedDate not supplied

Uncertainty analysis of the water balance technique for measuring seepage from animal waste lagoons.

Water balance measurements can be used to estimate seepage rates from animal waste lagoons and earthen storages. This method requires detailed measurements of depth changes and cumulative evaporation during 5- to 10-d periods. Quantifying the uncertainty surrounding the measurements is crucial if data from seepage tests are used to determine if lagoons are meeting engineering specifications and operating within regulatory guidelines. Uncertainty analyses, using a 95% confidence interval, were applied to field data collected during studies of animal waste lagoons in Kansas and Oklahoma. Changes in depth were measured with float-based recorders and evaporation was estimated from meteorological observations. Results showed that rate changes in depth could be measured to within +/-0.28 mm d(-1) or better when wind speeds at the start and end of the test were less than 4 m s(-1). Uncertainty in evaporation was the most significant factor affecting the seepage estimate, and surface temperature and relative humidity were the main sources of imprecision in the evaporation calculations. Evaporation could be estimated to within 10 to 20%, with the largest uncertainty occurring during windy conditions. Uncertainty in the calculated seepage rate increased as evaporation increased. When evaporation rates are low (e.g., <4 mm d(-1)), seepage can be estimated to within +/-0.5 mm d(-1) with 95% confidence. A precision of +/-0.25 mm d(-1) is possible when research-grade instruments are deployed under favorable weather conditions. A measurement duration of 5 d is adequate for most water balance tests. In many cases, precision of the water balance technique will be sufficient in determining if a working lagoon is within regulatory guidelines.

Animal Husbandry↗

PubMed2005

Effects of directional uncertainty on visually-guided joystick pointing.

Reaction times generally follow the predictions of Hick's law as stimulus-response uncertainty increases, although notable exceptions include the oculomotor system. Saccadic and smooth pursuit eye movement reaction times are independent of stimulus-response uncertainty. Previous research showed that joystick pointing to targets, a motor analog of saccadic eye movements, is only modestly affected by increased stimulus-response uncertainty; however, a no-uncertainty condition (simple reaction time to 1 possible target) was not included. Here, we re-evaluate manual joystick pointing including a no-uncertainty condition. Analysis indicated simple joystick pointing reaction times were significantly faster than choice reaction times. Choice reaction times (2, 4, or 8 possible target locations) only slightly increased as the number of possible targets increased. These data suggest that, as with joystick tracking (a motor analog of smooth pursuit eye movements), joystick pointing is more closely approximated by a simple/choice step function than the log function predicted by Hick's law.

Adult↗

PubMed1995

Result, error and uncertainty.

Several recent documents, from international standardization bodies, present the philosophical and statistical background for understanding the components of a measured value and its uncertainty, as well as the relevant nomenclature for their description. The value is the output of a function relating values from reading, calibrator, corrections and influence quantities. The corrected value may be regarded as the sum of a true value, bias of measurement procedure, laboratory deviation, and random error; in some cases there are also biases from aberrant sample and undetected mistakes. The contributions of laboratory deviation and random error vary with the precision conditions that must be specified. The uncertainty measures are no longer a sum of systematic errors and the positive square root of quadratically added random errors. Now, the measured corrected value is the best estimate and the components of its uncertainty, one from each input, are all expressed as statistically or non-statistically derived variances that are combined according to the function relating the input values. The positive square root of the outcome is the combined standard uncertainty that is regarded as a standard deviation from which an expanded uncertainty may be obtained by multiplying with a coverage factor.

Clinical Laboratory Techniques↗

PubMed1993

Optimal radiation beam profiles considering uncertainties in beam patient alignment.

The often large uncertainties that exist in beam patient alignment during radiation therapy may require modification of the incident beams to ensure an optimal delivered dose distribution to the target volume. This problem becomes increasingly severe when the required dose distribution of the incident beams becomes more heterogeneous. A simple analytical formula is derived for the case when the fraction number is high, and the desired relative dose variations are small. This formula adjusts the fluence distribution of the incident beam so that the resultant dose distribution will be as close as possible to the desired one considering the uncertainties in beam patient alignment. When sharp dose gradients are important, for instance at the border of the target volume, the problem is much more difficult. It is shown here that, if the tumor is surrounded by organs at risk, it is generally best to open up the field by about one standard deviation of the positional uncertainty--that is sigma/2 on each side of the target volume. In principle it is simultaneously desirable to increase the prescribed dose by a few per cent compared to the case where the positional uncertainty is negligible, in order to compensate for the rounded shoulders of the delivered dose distribution. When the tissues surrounding the tumor no longer are dose limiting even larger increases in field size may be advantageous. For more critical clinical situations the positional uncertainty may even limit the success of radiotherapy. In such cases one generally wants to create a steeper dose distribution than the underlying random Gaussian displacement process allows. The problem is then best handled by quantifying the treatment outcome under the influence of the stochastic process of patient misalignment. Either the coincidence with the desired dose distribution, or the expectation value of the probability of achieving complication-free tumor control is maximized under the influence of this stochastic process. It is shown that the most advantageous treatment is to apply beams that are either considerably widened or slightly widened and over flattened near the field edges for small and large fraction numbers respectively.

Dose-Response Relationship, Radiation↗

PubMedDate not supplied

Strategy under uncertainty.

At the heart of the traditional approach to strategy lies the assumption that by applying a set of powerful analytic tools, executives can predict the future of any business accurately enough to allow them to choose a clear strategic direction. But what happens when the environment is so uncertain that no amount of analysis will allow us to predict the future? What makes for a good strategy in highly uncertain business environments? The authors, consultants at McKinsey & Company, argue that uncertainty requires a new way of thinking about strategy. All too often, they say, executives take a binary view: either they underestimate uncertainty to come up with the forecasts required by their companies' planning or capital-budging processes, or they overestimate it, abandon all analysis, and go with their gut instinct. The authors outline a new approach that begins by making a crucial distinction among four discrete levels of uncertainty that any company might face. They then explain how a set of generic strategies--shaping the market, adapting to it, or reserving the right to play at a later time--can be used in each of the four levels. And they illustrate how these strategies can be implemented through a combination of three basic types of actions: big bets, options, and no-regrets moves. The framework can help managers determine which analytic tools can inform decision making under uncertainty--and which cannot. At a broader level, it offers executives a discipline for thinking rigorously and systematically about uncertainty and its implications for strategy.

Capital Expenditures↗

PubMedDate not supplied

[Higher mental functions and the systems analysis of behavior under conditions of uncertainty].

Superior psychical functions (skills) are usually formed in great subjective uncertainty conditions. Because of that exact knowledge of information mechanisms of behavior activity under uncertainty conditions is very importent. Some difficulties of traditional notions (classic behavior act model developed by P. K. Anokhin, systems quantization of behavior) are discussed. The model of probabilitive training allows to describe various training uncertainty conditions, and it operates as the Anokhin model in a specific case. The system-shaping factor in this model is an adaptive result. Afferent synthesis, aim for action, acceptor of the action result and the programme of actions have the traditional senses. Besides those it is proposed to use a concept of probability decision to alter the program of action, as well as an idea of memory buffer (results of search reactions). The organizational features of the functional system of behavior under great uncertainty conditions should be taken into account while specifying the informational mechanism responsible for systems quantization of behavior. The above mechanism can be used for explain the discreteness of an action in the program alteration process when the same quantum of behavior is implemented. These ideas are profitable for systems analysis of superior psychical functions, based on the reflex formation under environmental uncertainty conditions.

Animals↗

PubMed2002

Evaluation of uncertainties in urban hydrology: application to volumes and pollutant loads in a storage and settling tank.

It is necessary to assess adequately measurement uncertainties of experimental data in urban hydrology in order to draw pertinent and valuable conclusions from measurement results. This paper first gives a brief presentation of the concepts relative to standard uncertainties and to the law of propagation of uncertainties. Then it presents an example of calculation of the uncertainties in some quantities describing the behaviour of the Vénissieux (France) storage and settling tank during one rainfall event. These quantities are the flow rates and the volumes entering into the tank, the inflow and outflow mean concentrations and masses of TSS (Total Suspended Solids), and the TSS removal rate. Variographs are used to account for the autocorrelation of time series data. The results lead to the following relative uncertainties 8% for the total volume, 30% for the inflow concentration, 38% for the outflow concentration, 31% for the inflow mass, 39% for the outflow mass and 138% for the removal rate.

City Planning↗

PubMed2001

Sources of uncertainty and coping strategies used by family members of individuals living with end stage renal disease.

This article presents an analysis of the experience of family members of individuals with chronic renal disease undergoing dialysis therapy. Themes are derived from interviewing family members regarding the sources of uncertainty experienced and the types of coping strategies used to manage the stress related to uncertainty. The sample consisted of 41 family members including spouses, adult children, siblings, a niece, and a daughter-in-law from Eastern Canada. Data were collected from focus group interviews and thematic analysis was used to derive the themes. Emerging themes of uncertainty arose from many sources including: the patient's health, dialysis treatment, potential loss of the patient, and/or the availability of a kidney transplantation. The family members coped with the stress generated by the uncertainty by living each day as it comes, finding positive meaning, hoping for a transplant, and/or drawing on God's strength. Findings from this study provide direction for renal health care professionals to assist family members to prepare for, to understand, and to adapt to constant sources of uncertainty in their lives.

Activities of Daily Living↗

PubMed2003

Accounting for sensor calibration, data validation, measurement and sampling uncertainties in monitoring urban drainage systems.

Assessing the functioning and the performance of urban drainage systems on both rainfall event and yearly time scales is usually based on online measurements of flow rates and on samples of influent effluent for some rainfall events per year. In order to draw pertinent scientific and operational conclusions from the measurement results, it is absolutely necessary to use appropriate methods and techniques in order to i) calibrate sensors and analytical methods, ii) validate raw data, iii) evaluate measurement uncertainties, iv) evaluate the number of rainfall events to sample per year in order to determine performance indicator with a given uncertainty. Based an previous work, the paper gives a synthetic review of required and techniques, and illustrates their application to storage and settling tanks. Experiments show that, controlled and careful experimental conditions, relative uncertainties are about 20% for flow rates in sewer pipes, 6-10% for volumes, 25-35% for TSS concentrations and loads, and 18-276% for TSS removal rates. In order to evaluate the annual pollutant interception efficiency of storage and settling tanks with a given uncertainty, efforts should first be devoted to decrease the sampling uncertainty by increasing the number of sampled events.

Calibration↗

PubMed1992

Uncertainty and anxiety after mastectomy for breast cancer.

The purpose of this study was to determine the relationship between uncertainty and anxiety in women after mastectomy for breast cancer and to describe women's responses to partial or complete mastectomy for breast cancer during the early rehabilitative phase after surgery. A theoretical framework for the study was derived from the Scott, Oberst, and Dropkin Stress-Coping Model and from a review of the literature. Major study variables and variable measures were uncertainty, measured by the Mishel Uncertainty in Illness Scale (MUIS), and anxiety, measured by the State-Trait Anxiety Inventory (STAI). Twenty-five women admitted to two acute-care teaching hospitals for their first partial or modified radical mastectomy made up the convenience sample of this study. Data were collected 1-2 days before and 1-2 weeks after hospital discharge. From study findings, it was shown that only at the postdischarge testing was there a significant positive correlation between uncertainty and state anxiety. The development of appropriate interventions to assist breast cancer patients in dealing with the fears of recurrence and uncertainties regarding treatment effectiveness and sequelae has relevance for nursing practice.

Adult↗

PubMed2006

Uncertainty in experimental techniques for measuring sediment erodability.

There are many experimental methods currently utilized to measure sediment erodability and stability. When utilizing any of the available methods or devices to characterize erodability, one must understand the inherent uncertainty associated with each technique in relation to the application or expected measurement need. In addition, while some uncertainties are unique to a particular measurement device or technique, other uncertainties arise from variation in sediment conditions or properties. Several widely used devices and techniques are discussed with respect to their uncertainties and applicability for certain measurements. Finally, suggestions will be made on how to reduce uncertainty and manage it in model development.

Conservation of Natural Resources↗

PubMed1991

Validation of a Swedish version of the Mishel Uncertainty in Illness Scale.

Uncertainty and fear are realities patients often have to face in illness and hospitalization. Mishel has described how perceived uncertainty under these circumstances can affect the patient's coping strategies. The Mishel Uncertainty in Illness Scale (MUIS), along with a diagnosis-specific version of the MUIS, the Cardiovascular Population Scale, was translated into Swedish with the purpose of testing the usefulness of the scale on a Swedish coronary population. The sample included 60 patients, 40 males and 20 females, with coronary pain, cared for on two intensive coronary care units. The Swedish version of the MUIS seems to be in most instances a reliable instrument for measuring perceived uncertainty. Coefficient alpha was .82, compared with Mishel's reported .84. The reliability of the Cardiovascular Population Scale was .74. Study findings revealed that recency of prior hospitalization was significantly related to perceived uncertainty. Results point to the necessity of further validity testing.

Aged↗

PubMed1990

Uncertainty in pregnancy.

Although often unrecognized by care providers, uncertainty during pregnancy is universally experienced. The antecedents to uncertainty are exemplified with qualitative data from interviews with pregnant women. The following antecedents are discussed: (1) symptom patterns; (2) event familiarity; (3) event congruence; (4) cognitive capacity; (5) structure providers; and (6) credible authority. The importance of exploring uncertainty during pregnancy stems from the relationship between the stress associated with uncertainty and perinatal complications. Negative caregiver reactions to uncertainty that can intensify stress include ignorance, intolerance, and indifference. Suggestions for nursing assessments and interventions during prenatal care are provided.

Fear↗