Exponential-family random graph models (ERGMs) are probabilistic network models that are parametrized by sufficient statistics based on structural (i.e., graph-theoretic) properties. The ergm package for the R statistical computing system is a collection of tools for the analysis of network data within an ERGM framework. Many different network properties can be employed as sufficient statistics...

This paper presents statistical approaches to testing whether data are spherical in the topological sense, ie, they lie on a closed manifold with a hollow interior. We characterize the sphere by it’s Betti numbers and use the computational topology program PLEX [12] based on simplicial complexes to calculate the data’s Betti numbers. We use the parametric bootstrap approach to test the power of...

We collect data in order to increase our knowledge, but we always have some knowledge before we start. Our existing knowledge raises the questions for which we need more information, and it also guides us in deciding what further data to collect and how to collect it. Models allow us to generalise from specific observed data to a wider situation. When we analyse data we (usually) update our kno...

We derive a saddlepoint approximation to the pdf and cdf of both a singly and doubly noncentral F random variable and demonstrate its high accuracy over the entire parameter space. In contrast to usual saddlepoint applications, the method admits a closed form solution implying that, particularly for the doubly noncentral case, the proposed method is several orders of magnitude faster than exist...

Courtroom environments, which have been one of the last bastions of the oral tradition, are slowly morphing into cinematic display environments (Heintz, 2002). The persuasive oral rhetoric of lawyers is increasingly being replaced by compelling visual media displays presenting a range of digital evidence in a convincing and credible manner (Lederer, 2004; Schofield, 2007). There are a number of...

The task of the VAST 2010 Mini Challenge 2 was to characterize the spread of an epidemic outbreak. The analysis should take into consideration symptoms, mortality rates and temporal patterns of the disease. Finally, the outbreak should be compared across different locations searching for anomalies. For the preprocessing and the automated analysis of the data we used the Konstanz Information Min...

We revisit the problem of anonymous communication, in which users wish to send messages to each other without revealing their identities. We propose a novel framework to organize and compare anonymity definitions. In this framework, we present simple and practical definitions for anonymous channels in the context of computational indistinguishability. The notions seem to capture the intuitive p...

While political methodologists and other quantitative social scientists are the most obvious beneficiaries of the widespread availability of personal computers and associated software, virtually all social scientists rely on computers for a variety of research-related tasks, including but not limited to empirical analyses; word processing and typesetting; communicating and publishing via email ...

We introduce a statistical computing framework to address two important issues in spike sorting: flexible spike shape modeling and realtime spike clustering. In this framework, spikes are detected based on a nonparametric shape distribution; detected spikes are further grouped by an incremental clustering algorithm involving the second-order statistics–covariance matrix. We performed experiment...

In this manuscript both the classical and Bayesian analyses of a multiple step-stress model have been considered. The lifetime distributions of the experimental units at each stress level follow two-parameter generalized exponential distribution and they are related through the cumulative exposure model assumptions. Recently Abdel-Hamid and Al-Hussaini (Computational Statistics and Data Analysi...