We establish empirically using three different definitions of US cities that the upper tail obeys a Pareto law and not a lognormal distribution. We emphasize estimation of a switching point between the body of the city size distribution (which includes most cities) and its upper tail (which includes most of the population). For the 2000 Census Places data, in particular, our preferred model sug...

Vulnerability assessment of structures encounter many uncertainties like seismic excitations intensity and response of structures. The most common approach adopted to deal with these uncertainties is vulnerability assessment through fragility functions. Fragility functions exhibit the probability of exceeding a state namely performance-level as a function of seismic intensity. A common approach...

the implementation of different silvicultural systems can be effective on different characteristics of forest stands, such as stand structure and diameter distribution of trees. this study was carried out in shafaroud forests of gilan province of northern iran. the objectives of this research were 1) to evaluate the suitability of different probability distribution functions, including weibull,...

BACKGROUND In this study, we sought to analyze the stochastic behavior of Catherization Laboratories (Cath Labs) procedures in our institution. Statistical models may help to improve estimated case durations to support management in the cost-effective use of expensive surgical resources. METHODS We retrospectively analyzed all the procedures performed in the Cath Labs in 2012. The duration of...

Three methods of approximating the sum lognormal variates to a distribution were studied. They Wilkinson approximation, Monte Carlo version approximation and using estimated maximum likelihood parameters. The generated empirically simulation based on several conditions such as number in sum, sample points variates, are independent identically distributed (IID) also not (NIID) with Evaluation al...

This paper proposes a class of nonlinear stochastic volatility models. The proposed class encompasses many parametric stochastic volatility models that have appeared in the literature, including the well known lognormal stochastic volatility model. The new class is based on the Box-Cox transformation and offers an alternative to the one introduced in Andersen (1994). An advantage of our propose...

The effect of the microstructure on the electromigration failure development is analyzed. We investigate the influence of the statistical distribution of copper grain sizes on the electromigration time to failure distribution. Also, the effect of the microstructure on the formation and development of an electromigration-induced void is studied by simulation and the results are compared with exp...

The distribution function of a sum of lognormal random variables appears in several communication problems. Approximations are usually used for such distribution as no closed form nor bounds exist. Bounds can be very useful in assessing the performance of any given system. In this paper, we derive upper and lower bounds on the distribution function of a sum of independent lognormal random varia...