Now showing 1 - 6 of 6
  • Publication
    Mixed-Membership of Experts Stochastic Blockmodel
    (Cambridge University Press, 2016-03) ;
    Social network analysis is the study of how links between a set of actors are formed. Typically, it is believed that links are formed in a structured manner, which may be due to, for example, political or material incentives, and which often may not be directly observable. The stochastic blockmodel represents this structure using latent groups which exhibit different connective properties, so that conditional on the group membership of two actors, the probability of a link being formed between them is represented by a connectivity matrix. The mixed membership stochastic blockmodel extends this model to allow actors membership to different groups, depending on the interaction in question, providing further flexibility. Attribute information can also play an important role in explaining network formation. Network models which do not explicitly incorporate covariate information require the analyst to compare fitted network models to additional attributes in a post-hoc manner. We introduce the mixed membership of experts stochastic blockmodel, an extension to the mixed membership stochastic blockmodel which incorporates covariate actor information into the existing model. The method is illustrated with application to the Lazega Lawyers dataset. Model and variable selection methods are also discussed.
      302Scopus© Citations 9
  • Publication
    Review of Statistical Network Analysis: Models, Algorithms, and Software
    The analysis of network data is an area that is rapidly growing, both within and outside of the discipline of statistics. This review provides a concise summary of methods and models used in the statistical analysis of network data, including the Erdos–Renyi model, the exponential family class of network models, and recently developed latent variable models. Many of the methods and models are illustrated by application to the well-known Zachary karate dataset. Software routines available for implementing methods are emphasized throughout. The aim of this paper is to provide a review with enough detail about many common classes of network models to whet the appetite and to point the way to further reading.
      9479Scopus© Citations 83
  • Publication
    Bayesian variable selection for latent class analysis using a collapsed Gibbs sampler
    Latent class analysis is used to perform model based clustering for multivariate categorical responses. Selection of the variables most relevant for clustering is an important task which can affect the quality of clustering considerably. This work considers a Bayesian approach for selecting the number of clusters and the best clustering variables. The main idea is to reformulate the problem of group and variable selection as a probabilistically driven search over a large discrete space using Markov chain Monte Carlo (MCMC) methods. Both selection tasks are carried out simultaneously using an MCMC approach based on a collapsed Gibbs sampling method, whereby several model parameters are integrated from the model, substantially improving computational performance. Post-hoc procedures for parameter and uncertainty estimation are outlined. The approach is tested on simulated and real data.
      414Scopus© Citations 17
  • Publication
    Exponential family mixed membership models for soft clustering of multivariate data
    For several years, model-based clustering methods have successfully tackled many of the challenges presented by data-analysts. However, as the scope of data analysis has evolved, some problems may be beyond the standard mixture model framework. One such problem is when observations in a dataset come from overlapping clusters, whereby different clusters will possess similar parameters for multiple variables. In this setting, mixed membership models, a soft clustering approach whereby observations are not restricted to single cluster membership, have proved to be an effective tool. In this paper, a method for fitting mixed membership models to data generated by a member of an exponential family is outlined. The method is applied to count data obtained from an ultra running competition, and compared with a standard mixture model approach.
      248Scopus© Citations 2
  • Publication
    BayesLCA : An R Package for Bayesian Latent Class Analysis
    (Foundation for Open Access Statistics, 2014-11-25) ;
    The BayesLCA package for R provides tools for performing latent class analysis within a Bayesian setting. Three methods for fitting the model are provided, incorporating an expectation-maximization algorithm, Gibbs sampling and a variational Bayes approximation. The article briefly outlines the methodology behind each of these techniques and discusses some of the technical difficulties associated with them. Methods to remedy these problems are also described. Visualization methods for each of these techniques are included, as well as criteria to aid model selection.
      1237Scopus© Citations 46
  • Publication
    Identifying Patterns of Learner Behaviour: What Business Statistics Students do with Learning Resources
    (INFORMS, 2017-05) ;
    The interactions of early stage business students with learning resources over the duration of an introductory statistics module were analysed using latent class analysis. Four distinct behavioural groups were identified. While differing levels of face-to-face attendance and online interaction existed, all four groups failed to engage with online material in a timely manner. The four groups were found to demonstrate significantly different levels of attainment of the module learning outcomes. The patterns of behaviour of the different groups of students give insights as to which analytics education learning resources students use and how their use patterns relate to their level of attainment of the module learning outcomes.