Search results for " Probability"
showing 10 items of 2176 documents
Bayesian modeling of the evolution of male height in 18th century Finland from incomplete data.
2012
Abstract Data on army recruits’ height are frequently available and can be used to analyze the economics and welfare of the population in different periods of history. However, such data are not a random sample from the whole population at the time of interest, but instead is skewed since the short men were less likely to be recruited. In statistical terms this means that the data are left-truncated. Although truncation is well-understood in statistics a further complication is that the truncation threshold is not known, may vary from time to time, and auxiliary information on the threshold is not at our disposal. The advantage of the fully Bayesian approach presented here is that both the …
Cancer mortality inequalities in urban areas: a Bayesian small area analysis in Spanish cities
2011
incluye "Erratum to: Cancer mortality inequalities in urban areas: a Bayesian small area analysis in Spanish cities" BACKGROUND: Intra-urban inequalities in mortality have been infrequently analysed in European contexts. The aim of the present study was to analyse patterns of cancer mortality and their relationship with socioeconomic deprivation in small areas in 11 Spanish cities. METHODS: It is a cross-sectional ecological design using mortality data (years 1996-2003). Units of analysis were the census tracts. A deprivation index was calculated for each census tract. In order to control the variability in estimating the risk of dying we used Bayesian models. We present the RR of the censu…
Can bayesian models play a role in dental caries epidemiology? Evidence from an application to the BELCAP data set
2012
Objectives The aim of this study was to show the potential of Bayesian analysis in statistical modelling of dental caries data. Because of the bounded nature of the dmft (DMFT) index, zero-inflated binomial (ZIB) and beta-binomial (ZIBB) models were considered. The effects of incorporating prior information available about the parameters of models were also shown. Methods The data set used in this study was the Belo Horizonte Caries Prevention (BELCAP) study (Bohning et al. (1999)), consisting of five variables collected among 797 Brazilian school children designed to evaluate four programmes for reducing caries. Only the eight primary molar teeth were considered in the data set. A data aug…
Significance of the effective remnant liver volume in major hepatectomies
2005
The aim of this study is to identify the minimum safe amount of effective remnant liver volume (ERLV) in patients undergoing a major hepatectomy. Thirty-eight consecutive major hepatectomies (resection of ≥3 Couinaud segments) performed between July 1999 and March 2004 in which a frozen section liver biopsy was obtained were included. No patient had chronic viral hepatitis, cirrhosis, or cholestasis. The total liver volume (TLV) was calculated using the Vauthey formula, and the postsurgical liver volume (PSLV) was derived by subtracting the estimated volume of liver resected from the TLV. The PSLV minus the percentage of macrovesicular steatosis as nonfunctional liver was defined as the ef…
Detecting spatio-temporal mortality clusters of European countries by sex and age.
2018
[EN] Background: Mortality decreased in European Union (EU) countries during the last century. Despite these similar trends, there are still considerable differences in the levels of mortality between Eastern and Western European countries. Sub-group analysis of mortality in Europe for different age and sex groups is common, however to our knowledge a spatio-temporal methodology as in this study has not been applied to detect significant spatial dependence and interaction with time. Thus, the objective of this paper is to quantify the dynamics of mortality in Europe and detect significant clusters of mortality between European countries, applying spatio-temporal methodology. In addition, th…
Les followers ont-ils vraiment de l'importance dans le modèle de Stackelberg?
2011
In this paper, we consider a T-stage linear model of Stackelberg oligopoly. First, we show geometrically and analytically that under the two conditions of linear market demand and identical constant marginal costs, the T-stage Stackelberg model reduces to a model where T oligopolies exploit residual demand sequentially. At any stage, leaders behave as if followers did not matter. Second, we study social welfare and convergence toward competitive equilibrium. Especially, we consider the velocity of convergence as the number of firms increases. The convergence is faster when reallocating firms from the most to the less populated cohort until equalizing the size of all cohorts.
Demand for and Pricing of Mobile Internet: Evidence from a Real-World Pricing Experiment
2006
Commercialization of innovations frequently stumbles. A prominent recent example are the early (i.e. pre3G)mobile phone-enabled Internet services, whose European takeup was slower than expected. To determine why, we build a structural model of demand for such services and estimate it using consumerlevel panel data from a real world pricing experiment. The experiment allows for a decomposition of the number of wireless connections into the number of needs instances where a consumer would establish a connection if the price were zero and the conditional probability of establishing a connection. We find that needs were plenty and potential consumer surplus several magnitudes higher than that a…
Minimising value-at-risk in a portfolio optimisation problem using a multi-objective genetic algorithm
2011
[EN] In this paper, we develop a general framework for market risk optimisation that focuses on VaR. The reason for this choice is the complexity and problems associated with risk return optimisation (non-convex and non-differential objective function). Our purpose is to obtain VaR efficient frontiers using a multi-objective genetic algorithm (GA) and to show the potential utility of the algorithm to obtain efficient portfolios when the risk measure does not allow calculating an optimal solution. Furthermore, we measure differences between VaR efficient frontiers and variance efficient frontiers in VaR-return space and we evaluate out-sample capacity of portfolios on both bullish and bearis…
Bayesian forecasting with the Holt–Winters model
2010
Exponential smoothing methods are widely used as forecasting techniques in inventory systems and business planning, where reliable prediction intervals are also required for a large number of series. This paper describes a Bayesian forecasting approach based on the Holt–Winters model, which allows obtaining accurate prediction intervals. We show how to build them incorporating the uncertainty due to the smoothing unknowns using a linear heteroscedastic model. That linear formulation simplifies obtaining the posterior distribution on the unknowns; a random sample from such posterior, which is not analytical, is provided using an acceptance sampling procedure and a Monte Carlo approach gives …
Is the cardholder an efficient alarm system to detect credit card incidents?
2015
There is a growing tendency in credit card industry to increase the contribution of the smallest players, the cardholders, in the detection of card incidents. This article examines whether cardholders are efficient at detecting/communicating incidents of theft, loss or fraudulent use of their cards. The analysis focuses on whether they demonstrate enough speed of response to support a risk control subsystem by the issuer. The research follows a completely new approach showing how the issue can be handled by applying the concept of elasticity, a notion just recently exported from economics to the field of statistics by linking it with the reverse hazard rate. The issue is focused on the anal…