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Statistical Methodology Commons

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Full-Text Articles in Statistical Methodology

Adventures In Library Salary Surveys, Scott L. Schaffer Aug 2012

Adventures In Library Salary Surveys, Scott L. Schaffer

UVM Libraries Conference Day

Salary surveys are an important tool for the library community and the administrators and boards responsible for the oversight of libraries. However, such assessments must be constructed and analyzed with great care. The Vermont Library Association Personnel Committee has conducted three salary surveys over the past several years, one focusing on academic libraries and two on public libraries. Significant issues have included confidentiality, participation rate, definitions, length and difficulty of questions, collection of data, and representativeness. Suggestions and lessons learned will be shared.


Modeling Dependence Using Skew T Copulas: Bayesian Inference And Applications, Michael S. Smith, Quan Gan, Robert Kohn Dec 2011

Modeling Dependence Using Skew T Copulas: Bayesian Inference And Applications, Michael S. Smith, Quan Gan, Robert Kohn

Michael Stanley Smith

[THIS IS AN AUGUST 2010 REVISION THAT REPLACES ALL PREVIOUS VERSIONS.]

We construct a copula from the skew t distribution of Sahu, Dey & Branco (2003). This copula can capture asymmetric and extreme dependence between variables, and is one of the few copulas that can do so and still be used in high dimensions effectively. However, it is difficult to estimate the copula model by maximum likelihood when the multivariate dimension is high, or when some or all of the marginal distributions are discrete-valued, or when the parameters in the marginal distributions and copula are estimated jointly. We therefore propose …


Estimation Of Copula Models With Discrete Margins Via Bayesian Data Augmentation, Michael S. Smith, Mohamad A. Khaled Dec 2011

Estimation Of Copula Models With Discrete Margins Via Bayesian Data Augmentation, Michael S. Smith, Mohamad A. Khaled

Michael Stanley Smith

Estimation of copula models with discrete margins is known to be difficult beyond the bivariate case. We show how this can be achieved by augmenting the likelihood with latent variables, and computing inference using the resulting augmented posterior. To evaluate this we propose two efficient Markov chain Monte Carlo sampling schemes. One generates the latent variables as a block using a Metropolis-Hasting step with a proposal that is close to its target distribution, the other generates them one at a time. Our method applies to all parametric copulas where the conditional copula functions can be evaluated, not just elliptical copulas …