In this paper we compare two different approaches to deal with lognormal variables/observations, and hence their errors, in a 3-dimensional variational data assimilation framework. The first approach uses a transform to make the lognormal random variable into a normal random variable and hence use current data assimilation techniques. The second approach uses the correct distribution for a coll...

Recently, I became interested in a current debate over whether file size distributions are best modelled by a power law distribution or a lognormal distribution. In trying to learn enough about these distributions to settle the question, I found a rich and long history, spanning many fields. Indeed, several recently proposed models from the computer science community have antecedents in work fr...

• In the insurance area, especially based on observations of the number of claims, N(w), corresponding to an exposure w, and on observations of the total amount of claims incurred, Y (w), the risk theory arises to quantify risks and to fit models of pricing and insurance company ruin. However, the main problem is the complexity to obtain the distribution function of Y (w) and, consequently, the...

considering the importance of biodiversity conservation and protection assessment activities, the present filed study was conducted with aim to compare vegetation diversity of two areas with different levels of protection including ghorkhod protected area with seasonal grazing and golestan national park without grazing, during spring and summer of 2011. four replications were selected in each a...

Knowing the distribution of fitness effects (DFE) of new mutations is important for several topics in evolutionary genetics. Existing computational methods with which to infer the DFE based on DNA polymorphism data have frequently assumed that the DFE can be approximated by a unimodal distribution, such as a lognormal or a gamma distribution. However, if the true DFE departs substantially from ...

Mike Thelwall, Statistical Cybermetrics Research Group, University of Wolverhampton, UK. Many different citation-based indicators are used by researchers and research evaluators to help evaluate the impact of scholarly outputs. Although the appropriateness of individual citation indicators depends in part on the statistical properties of citation counts, there is no universally agreed best-fitt...

We investigate two important properties of real data: diversity and log-normality. Log-normality accounts for the fact that data follow the lognormal distribution, whereas diversity measures variations of the attributes in the data. To our knowledge, these two inherent properties have not been paid much attention from the machine learning community, especially from the topic modeling community....

The frequency distribution of the extreme ultraviolet (EUV) emission line intensities in the quiet Sun has in the past often been modelled using two Gaussians. This gives adequate fits to observed distributions of average statistical significance. In this paper we test this and other distribution functions against observed distributions with exceptional statistical significance. The data were o...

A review of the author’s findings over four decades will show that the lognormal probability density function can be fit to many types of positive-variate radiation measurement and response data. The cumulative lognormal plot on probability vs. logarithmic coordinate graph paper can be shown to be useful in comparing trends in exposure distributions or responses under differing conditions or ex...