A non-parametric framework for estimating threshold limit values

dc.contributor.authorSalanti, G.en
dc.contributor.authorUlm, K.en
dc.date.accessioned2015-11-24T19:40:05Z
dc.date.available2015-11-24T19:40:05Z
dc.identifier.issn1471-2288-
dc.identifier.urihttps://olympias.lib.uoi.gr/jspui/handle/123456789/24300
dc.rightsDefault Licence-
dc.subjectAir Pollutants, Occupational/adverse effects/*analysisen
dc.subjectAlgorithmsen
dc.subjectBronchitis, Chronic/etiologyen
dc.subjectData Collectionen
dc.subjectDust/analysisen
dc.subjectHumansen
dc.subject*Likelihood Functionsen
dc.subjectLogistic Modelsen
dc.subjectModels, Statisticalen
dc.subjectRegression Analysisen
dc.subjectRisk Assessmenten
dc.subject*Statistics, Nonparametricen
dc.subject*Threshold Limit Valuesen
dc.titleA non-parametric framework for estimating threshold limit valuesen
heal.abstractBACKGROUND: To estimate a threshold limit value for a compound known to have harmful health effects, an 'elbow' threshold model is usually applied. We are interested on non-parametric flexible alternatives. METHODS: We describe how a step function model fitted by isotonic regression can be used to estimate threshold limit values. This method returns a set of candidate locations, and we discuss two algorithms to select the threshold among them: the reduced isotonic regression and an algorithm considering the closed family of hypotheses. We assess the performance of these two alternative approaches under different scenarios in a simulation study. We illustrate the framework by analysing the data from a study conducted by the German Research Foundation aiming to set a threshold limit value in the exposure to total dust at workplace, as a causal agent for developing chronic bronchitis. RESULTS: In the paper we demonstrate the use and the properties of the proposed methodology along with the results from an application. The method appears to detect the threshold with satisfactory success. However, its performance can be compromised by the low power to reject the constant risk assumption when the true dose-response relationship is weak. CONCLUSION: The estimation of thresholds based on isotonic framework is conceptually simple and sufficiently powerful. Given that in threshold value estimation context there is not a gold standard method, the proposed model provides a useful non-parametric alternative to the standard approaches and can corroborate or challenge their findings.en
heal.accesscampus-
heal.fullTextAvailabilityTRUE-
heal.identifier.primary10.1186/1471-2288-5-36-
heal.identifier.secondaryhttp://www.ncbi.nlm.nih.gov/pubmed/16274473-
heal.identifier.secondaryhttp://www.biomedcentral.com/1471-2288/5/36-
heal.journalNameBMC Med Res Methodolen
heal.journalTypepeer-reviewed-
heal.languageen-
heal.publicationDate2005-
heal.recordProviderΠανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικήςel
heal.typejournalArticle-
heal.type.elΆρθρο Περιοδικούel
heal.type.enJournal articleen

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