Search results for " Log-Normal"
showing 3 items of 3 documents
Pareto or log-normal? Best fit and truncation in the distribution of all cities
2015
In the literature, the distribution of city size is a controversial issue with two common contenders: the Pareto and the log-normal. While the first is most accredited when the distribution is truncated above a certain threshold, the latter is usually considered a better representation for the untruncated distribution of all cities. In this paper, we reassess the empirical evidence on the best-fitting distribution in relation to the truncation point issue. Specifically, we provide a comparison among four recently proposed approaches and alternative definitions of U.S. cities. Our results highlight the importance to look at issue of the best-fitting distribution together with the truncation …
Evolved factor method for service life prediction of building components
2013
Key issues in the production process associated with construction are the implementation of quality and sustainability principles. Indeed, it is increasingly important in the maintenance of quality levels provided by materials, components and building structures, especially after the recent Regulation (EU) No. 305/2011. This document introduced the seventh requirement for the sustainable use of natural resources, guaranteeing the durability of construction products, thus being planned. The international standard for the assessment of durability of building materials and components is the ISO 15686 - Buildings and constructed assets - Service life planning, providing the definition of the Re…
Pareto or log-normal? A recursive-truncation approach to the distribution of (all) cities
2012
Traditionally, it is assumed that the population size of cities in a country follows a Pareto distribution. This assumption is typically supported by finding evidence of Zipf's Law. Recent studies question this finding, highlighting that, while the Pareto distribution may fit reasonably well when the data is truncated at the upper tail, i.e. for the largest cities of a country, the log-normal distribution may apply when all cities are considered. Moreover, conclusions may be sensitive to the choice of a particular truncation threshold, a yet overlooked issue in the literature. In this paper, then, we reassess the city size distribution in relation to its sensitivity to the choice of truncat…