We investigate the transformation laws of coordinates in generalizations of special relativity with two observer-independent scales. The request of covariance leads to simple formulas if one assumes noncanonical Poisson brackets, corresponding to noncommuting spacetime coordinates. ∗email: [email protected]

The Russian establishment—politicians, agricultural officials, corporate farm managers, the media — firmly believe that inadequate access to credit is one of the major factors constraining the growth of the agricultural sector. In technical terms, they in effect claim that Russian agriculture faces credit rationing. In this article, we apply discrete regression analysis to study the determinant...

Department of Statistical Science, Duke University March 24, 2008 We show the posterior consistency of certain nonparametric regression models using Lévy Random field priors. An easily verifiable sufficient condition is derived for the posterior consistency to hold in popular models which use Lévy random fields for regression and function estimation. We apply our results to a Poisson regression...

The purpose of this project is to show observations taken from the Iterative Proportional Scaling algorithm when used with data taken from Hierarchical LogLinear Models. We show with empirical proof that the difference between decomposable and non-decomposable graph models used is not exceedingly different. For the purpose of this project we looked at the properties of the two, three, and four ...

Count models are a subset of discrete response regression models. Count data are distributed as non-negative integers, are intrinsically heteroskedastic, right skewed, and have a variance that increases with the mean. Example count data include such situations as length of hospital stay, the number of a certain species of fish per defined area in the ocean, the number of lights displayed by fir...

We consider a bivariate Poisson model that is based on the lognormal heterogeneity model. Two recent applications have used this model. We suggest that the correlation estimated in their model frameworks is an ambiguous measure of the correlation of the variables of interest, and may substantially overstate it. We conclude with a detailed application of the proposed method using the data employ...

Various authors [3, 9, 11, 12] have noted that Poisson regression can be used to analyze cohort survival data (see Cohort Study). This formulation also leads to a unification of risk estimation based on internal comparison of rates among members of a cohort with various exposure levels and classical epidemiologic methods based on external rates that yield standardized mortality ratios or standa...

Count data with extra zeros are common in many medical applications. The zero-inflated Poisson (ZIP) regression model is useful to analyse such data. For hierarchical or correlated count data where the observations are either clustered or represent repeated outcomes from individual subjects, a class of ZIP mixed regression models may be appropriate. However, the ZIP parameter estimates can be s...

Critics of voting by mail express concern over its impact on civil society. For example, Thompson (2004) posits that voting by mail limits electoral civic engagement by preventing the temporal norm of simultaneity on Election Day. I, however, find that the open ballot system of voting by mail promotes deliberation, which encourages civic engagement. This study tests if voting by mail increases ...