Search results for "Uncertainty"

UNCERTAINTY EVALUATION IN THE LOW-FREQUENCY MAGNETIC FIELD MEASUREMENTS WITH REGARD TO EXPOSURE OF HUMAN BEINGS

2010

The paper deals with low-frequency magnetic field measurements, with regard to exposure of human beings, carried out by using a broadband and isotropic instrument. These measurements are characterized by a very high uncertainty values if compared with the ones usually related to other electrical measurements. These large uncertainty values imply a high risk of wrong decision when there is the need to establish if a site complies or does not comply with a specified emission limits. A reduction of the uncertainty values implies a reduction of the risk. With this aim, in the paper we propose an approach which, in case of fields generated by electric power systems (50 or 60 Hz), allows an effec…

Bayesian semiparametric long memory models for discretized event data

2020

We introduce a new class of semiparametric latent variable models for long memory discretized event data. The proposed methodology is motivated by a study of bird vocalizations in the Amazon rain forest; the timings of vocalizations exhibit self-similarity and long range dependence. This rules out Poisson process based models where the rate function itself is not long range dependent. The proposed class of FRActional Probit (FRAP) models is based on thresholding, a latent process. This latent process is modeled by a smooth Gaussian process and a fractional Brownian motion by assuming an additive structure. We develop a Bayesian approach to inference using Markov chain Monte Carlo and show g…

Modelling phytoplankton in boreal lakes

2014

Prediction and interpolation of time series by state space models

2015

Artikkeliväitöskirja. Sisältää yhteenveto-osan ja neljä artikkelia. Article dissertation. Contains an introduction part and four articles. A large amount of data collected today is in the form of a time series. In order to make realistic inferences based on time series forecasts, in addition to point predictions, prediction intervals or other measures of uncertainty should be presented. Multiple sources of uncertainty are often ignored due to the complexities involved in accounting them correctly. In this dissertation, some of these problems are reviewed and some new solutions are presented. A state space approach is also advocated for an e cient and exible framework for time series forecas…

Unawareness, Priors and Posteriors

2008

Abstract. This note contains first thoughts on awareness of unawareness in a simple dynamic context where a decision situation is repeated over time. The main consequence of increasing awareness is that the model the decision maker uses, and the prior which it contains, becomes richer over time. The decision maker is prepared to this change, and we show that if a projection-consistency axiom is satisfied unawareness does not affect the value of her estimate of a payoff-relevant conditional probability (although it may weaken confidence in such estimate). Probability-zero events however pose a challenge to this axiom, and if that fails, even estimate values will be different if the decision …

Persistent joblessness and fertility intentions

2019

Background: The vast majority of demographic studies have approached and operationalised the notion of economic uncertainty using snapshot indicators. Hence, the complexity and diversity of individuals' employment careers were largely hidden. We posit that the persistence of joblessness - that is, repeated and close spells of joblessness - represents a crucial marker of economic uncertainty in the realm of fertility (intention) research. Objective: We aim to explore the association between persistent joblessness of both members of the couple and women's fertility intentions among those who entered employment at least once in the last five years. Methods: We develop an index of persistent jo…

Calculating confidence intervals for impact numbers

2006

Abstract Background Standard effect measures such as risk difference and attributable risk are frequently used in epidemiological studies and public health research to describe the effect of exposures. Recently, so-called impact numbers have been proposed, which express the population impact of exposures in form of specific person or case numbers. To describe estimation uncertainty, it is necessary to calculate confidence intervals for these new effect measures. In this paper, we present methods to calculate confidence intervals for the new impact numbers in the situation of cohort studies. Methods Beside the exposure impact number (EIN), which is equivalent to the well-known number needed …

Implementation of dosimetry equipment and phantoms at the MedAustron light ion beam therapy facility

2017

Purpose: To describe the implementation of dosimetry equipment and phantoms into clinical practice of light ion beam therapy facilities. This work covers standard dosimetry equipment such as computerized water scanners, films, 2D-array, thimble and plane parallel ionization chambers, but also dosimetry equipment specifically devoted to the pencil beam scanning delivery technique such as water columns, scintillating screens or multi-layer ionization chambers. Method: Advanced acceptance testing procedures developed at MedAustron and complementary to the standard acceptance procedures proposed by the manufacturer are presented. Detailed commissioning plans have been implemented for each piece…

Recent Insights Into Cyberchondria.

2020

Purpose of Review The construct of cyberchondria was introduced relatively recently. This article aims to review the conceptualization, theoretical basis and correlates of cyberchondria, as well as its prevention and management. Recent Findings Although there is no consensus, most definitions of cyberchondria emphasize online health research associated with heightened distress or anxiety. The two theoretical models of cyberchondria involve reassurance seeking and specific metacognitive beliefs. Cyberchondria has relationships with health anxiety, problematic Internet use and symptoms of obsessive-compulsive disorder, with public health implications pertaining to functional impairment and al…

Uncertainty on radiation doses estimated by biological and retrospective physical methods

2018

International audience; Biological and physical retrospective dosimetry are recognised as key techniques to provide individual estimates of dose following unplanned exposures to ionising radiation. Whilst there has been a relatively large amount of recent development in the biological and physical procedures, development of statistical analysis techniques has failed to keep pace. The aim of this paper is to review the current state of the art in uncertainty analysis techniques across the 'EURADOS Working Group 10- Retrospective dosimetry' members, to give concrete examples of implementation of the techniques recommended in the international standards, and to further promote the use of Monte…