1,721,044 research outputs found
Fuzzy sets and possiblity measures. An introduction into the theory and examples of applications
No full textThe author reports on a literature search on fuzzy sets. Fuzzy sets differ from classical sets in the following sense: elements can partly belong to fuzzy sets, whereas elements do or don't belong to classical sets. Fuzzy sets can be generalized to fuzzy relations between elements ; fuzzy Markovian chains, that describe transitions between elements ; fuzzy functions ; fuzzy numbers ; fuzzy reasoning based on fuzzy relations ; fuzzy inclusion ; and fuzzy partitions. The possibility measure is a fuzzy translation of the probability measure: it quantifies the possibility of an event instead of the probability. Three applications of fuzzy sets and possibility measures have been elaborated: fuzzy linear regression, the fuzzy shortest path problem and fuzzy multi-criteria analysis. On the basis of the fuzzy shortest path problem (the interpretations of) the possibility measure and the probability measure are compared.RIV
demographic models for scenario-studies
No full textA demographic model is described that has been used in scenario-research for calculating future population numbers. The demographic model developed is a discrete Markov-model. It calculates the changes in the Netherlands population numbers for each year successively. the model is specially developed to analyse the consequences of alternative assumptionswith respect to future death, birth, and migration developments. If necessary the model also makes use of administrative corrections. The results of the demographic model are compared with the known population numbers for the past. For the futre the results are compared with the projections published by the Netherlands Central Bureau of Statistics. the results of this extensive demographic model are also compared with those of some sparse models. These sparse models have a fewer number of transition probabilities between age classes to be estimated. It is concluded that the more extensive demographic models generally give better results than the sparse odels. These sparse models however give rather good results for general approximations when the heterogeneity within the age clases is modelled explicitly. The future population numbers for the oldest age group(s) are generally overestimated, presumably due to the effect of using the registration numbers in the models. For the CBS medium variant the calculated future population numbers differ less from the CBS population forecasts than for the low and high variant.DGVGZ/STABO-ST
Veroudering en sterfte. Resultaten op basis van de Zutphen-studie
No full textThe link between competing death risks and the change of risk factor levels over time has been analysed using data from the Zutphen-Study and the model of Manton&Stallard. The Zutphen-cohort consists of 878 men, initially with te ages of 40-59 years, that have been followed since 1960. The model of Manton&Stallard describes the change of the distribution of the risk factor levels of a cohort over time taking into account mortality and the change of levesl within individuals. The hazard function used is similar to the one used in the Cox proportional hazards model. For almost the same combinations of risk factors and causes of death significant effects have been found as in Cox analyses. However, using current instead of baseline risk factor measurement values result in smaller effects probably due to medication (for total cholesterol and systolic bloodpressure) or in larger effects probably due to a reverse causal relation (for BMI and lung cancer). The most interesting and striking rsults were found with respect to the risk factor changes over age. We found positive age-trends for all risk factors (although non-significant for cholesterol), whereas the results of simple regression analyses were not that clear. More specific results relate to the interactions with respect to the deterministic and random changes. The results of the analyses will be used for the further development of the chronic diseases modelling tools. That means, the refinement of the modelling of the changes of the risk factors mentioned above over age, and the relation (interaction) between thes changesHet verband tussen concurrerende doodsoorzaken en de verandering van risicofactorniveau's over de tijd is onderzocht met behulp van gegevens van de Zutphen-Studie en het model van Manton&Stallard. Het Zutphen-cohort bestaat uit 878 mannen, aanvankelijk met leeftijd 40-59 jaar, die gevolgd zijn vanaf 1960. Het model van Manton&Stallard beschrijft de veranderingen van de verdeling van de risicofactorniveau's van een cohort als functie van selectieve sterfte en de risicofactorniveau-veranderingen binnen individuen. De gebruikte mortaliteits hazard functie lijkt op die van het Cox model. Voor vrijwel dezelfde combinaties van risicofactoren en doodsoorzaken werden significante modelparameters gevonden. Het gebruik van actuele in plaats van 'baseline' meetwaarden leidde tot kleinere effecten voor bloeddruk en cholesterol (te verklaren door medicijngebruik) en een groter effect voor BMI en longkanker (te verklaren door een omgekeerd verband). De meest opvallende en interessante resultaten werden gevonden met betrekking tot de risicofactor veranderingen. Wij vonden positieve veranderingen met de leeftijd (hoewel niet-significant voor cholesterol), in tegenstelling tot de uitkomsten van eenvoudige regressie analyses. Meer specifieke resultaten werden gevonden met betrekking tot de risicofactor specifieke deterministische en toevalsveranderingen. De resultaten van de analyses worden gebruikt bij de verdere ontwikkeling van het chronische ziekten model
Veroudering en sterfte. Resultaten op basis van de Zutphen-studie
No full textHet verband tussen concurrerende doodsoorzaken en de verandering van risicofactorniveau's over de tijd is onderzocht met behulp van gegevens van de Zutphen-Studie en het model van Manton&Stallard. Het Zutphen-cohort bestaat uit 878 mannen, aanvankelijk met leeftijd 40-59 jaar, die gevolgd zijn vanaf 1960. Het model van Manton&Stallard beschrijft de veranderingen van de verdeling van de risicofactorniveau's van een cohort als functie van selectieve sterfte en de risicofactorniveau-veranderingen binnen individuen. De gebruikte mortaliteits hazard functie lijkt op die van het Cox model. Voor vrijwel dezelfde combinaties van risicofactoren en doodsoorzaken werden significante modelparameters gevonden. Het gebruik van actuele in plaats van 'baseline' meetwaarden leidde tot kleinere effecten voor bloeddruk en cholesterol (te verklaren door medicijngebruik) en een groter effect voor BMI en longkanker (te verklaren door een omgekeerd verband). De meest opvallende en interessante resultaten werden gevonden met betrekking tot de risicofactor veranderingen. Wij vonden positieve veranderingen met de leeftijd (hoewel niet-significant voor cholesterol), in tegenstelling tot de uitkomsten van eenvoudige regressie analyses. Meer specifieke resultaten werden gevonden met betrekking tot de risicofactor specifieke deterministische en toevalsveranderingen. De resultaten van de analyses worden gebruikt bij de verdere ontwikkeling van het chronische ziekten model.The link between competing death risks and the change of risk factor levels over time has been analysed using data from the Zutphen-Study and the model of Manton&Stallard. The Zutphen-cohort consists of 878 men, initially with te ages of 40-59 years, that have been followed since 1960. The model of Manton&Stallard describes the change of the distribution of the risk factor levels of a cohort over time taking into account mortality and the change of levesl within individuals. The hazard function used is similar to the one used in the Cox proportional hazards model. For almost the same combinations of risk factors and causes of death significant effects have been found as in Cox analyses. However, using current instead of baseline risk factor measurement values result in smaller effects probably due to medication (for total cholesterol and systolic bloodpressure) or in larger effects probably due to a reverse causal relation (for BMI and lung cancer). The most interesting and striking rsults were found with respect to the risk factor changes over age. We found positive age-trends for all risk factors (although non-significant for cholesterol), whereas the results of simple regression analyses were not that clear. More specific results relate to the interactions with respect to the deterministic and random changes. The results of the analyses will be used for the further development of the chronic diseases modelling tools. That means, the refinement of the modelling of the changes of the risk factors mentioned above over age, and the relation (interaction) between thes changesRIV
Comparison of Tobacco Control Scenarios: Quantifying Estimates of Long-term health impact using the DYNAMO-HIA modeling tool.
Full text linkThere are several types of tobacco control interventions/policies which can change future smoking exposure. The most basic intervention types are 1) smoking cessation interventions 2) preventing smoking initiation and 3) implementation of a nationwide policy affecting quitters and starters simultaneously. The possibility for dynamic quantification of such different interventions is key for comparing the timing and size of their effects
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
The Cumulative Sum (Cusum) quality control scheme. A new control scheme for production processes with a declining quality level
No full textThe report starts with an introduction into the Cusum quality control scheme. This scheme is meant to improve the operating characteristic in case of small samples. Therefore the likelihood ratios of some bad parameter value with respect to the good parameter value are being summed up for successive samples. It is shown how to extend the original one-sided univariate Cusum scheme into two-sided and multivariate schemes. A computer program is presented that can be used to fix the parameter values of the Cusum scheme. Finally, information is given on the application of the Cusum scheme within the BCR project for reference materials in water and food microbiology.RIV
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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