نتایج جستجو برای: lognormal

تعداد نتایج: 2539  

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2014
H J H Brouwers

This paper addresses the packing and void fraction of polydisperse particles with a lognormal size distribution. It is demonstrated that a binomial particle size distribution can be transformed into a continuous particle-size distribution of the lognormal type. Furthermore, an original and exact expression is derived that predicts the packing fraction of mixtures of particles with a lognormal d...

Journal: :Statistics in medicine 2007
Sander Greenland

Data augmentation priors facilitate contextual evaluation of prior distributions and the generation of Bayesian outputs from frequentist software. Previous papers have presented approximate Bayesian methods using 2x2 tables of 'prior data' to represent lognormal relative-risk priors in stratified and regression analyses. The present paper describes extensions that use the tables to represent ge...

2017
Enrique Calderín-Ojeda Kevin Fergusson Xueyuan Wu

Generalized linear models might not be appropriate when the probability of extreme events is higher than that implied by the normal distribution. Extending the method for estimating the parameters of a double Pareto lognormal distribution (DPLN) in Reed and Jorgensen (2004), we develop an EM algorithm for the heavy-tailed Double-Pareto-lognormal generalized linear model. The DPLN distribution i...

2013
Tuyatsetseg Badarch Otgonbayar Bataa

This paper presents parametric probability density models for call holding time (CHT)based on the actual data collected for over a week from the IP based public Emergency Information Network (EIN) in Mongolia. When the set of chosen candidates of Gamma distribution family is fitted to the call holding time data, it is observed that the whole area in the CHT empirical histogram is underestimated...

2015
Marwane Ben Hcine Ridha Bouallegue

Several methods have been proposed to approximate the sum of lognormal RVs. However the accuracy of each method relies highly on the region of the resulting distribution being examined, and the individual lognormal parameters, i.e., mean and variance. There is no such method which can provide the needed accuracy for all cases. This paper propose a universal yet very simple approximation method ...

2001
Michael Mitzenmacher

Power law distributions are an increasingly common model for computer science applications; for example, they have been used to describe file size distributions and inand out-degree distributions for the Web and Internet graphs. Recently, the similar lognormal distribution has also been suggested as an appropriate alternative model for file size distributions. In this paper, we briefly survey s...

2005
J. Salo L. Vuokko P. Vainikainen Jari Salo Lasse Vuokko

Received signal power in mobile wireless communications is often modelled as a product of three factors: distance-dependent average path loss, lognormal variation in the local mean power level (shadow fading), and small-scale fading due to movement in the order of a wavelength. Of these three factors, the least well understood is the shadow fading, the lognormality of which is usually explained...

2010
HANFENG CHEN

Comparisons of two lognormal population means are investigated. For large samples, the conventional test for significance of the population means is the ordinary Student /-test with normal critical value. By Chen and Loh's result (Ann. Statist. 20 (1992)), however, the transformed i-test based on legdata is asymptotically more powerful than the ordinary i-test. In this paper, a new power transf...

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