Worcester Polytechnic Institute Electronic Theses and Dissertations Collection

Title page for ETD etd-121506-145455


Document Typethesis
Author NameMarjerison, William M
Email Address wmarjeri at fastmail.fm
URNetd-121506-145455
TitleBayesian Logistic Regression with Spatial Correlation: An Application to Tennessee River Pollution
DegreeMS
DepartmentMathematical Sciences
Advisors
  • Balgobin Nandram, Advisor
  • Keywords
  • logistic regression
  • Bayesian statistics
  • MCMC
  • spatial statistics
  • Date of Presentation/Defense2006-12-15
    Availability unrestricted

    Abstract

    We analyze data (length, weight and location) from a study done by the Army Corps of Engineers along the Tennessee River basin in the summer of 1980. The purpose is to predict the probability that a hypothetical channel catfish at a location studied is toxic and contains 5 ppm or more DDT in its filet. We incorporate spatial information and treate it separetely from other covariates. Ultimately, we want to predict the probability that a catfish from the unobserved location is toxic.

    In a preliminary analysis, we examine the data for observed locations using frequentist logistic regression, Bayesian logistic regression, and Bayesian logistic regression with random effects. Later we develop a parsimonious extension of Bayesian logistic regression and the corresponding Gibbs sampler for that model to increase computational feasibility and reduce model parameters. Furthermore, we develop a Bayesian model to impute data for locations where catfish were not observed. A comparison is made between results obtained fitting the model to only observed data and data with missing values imputed. Lastly, a complete model is presented which imputes data for missing locations and calculates the probability that a catfish from the unobserved location is toxic at once.

    We conclude that length and weight of the fish have negligible effect on toxicity. Toxicity of these catfish are mostly explained by location and spatial effects. In particular, the probability that a catfish is toxic decreases as one moves further downstream from the source of pollution.

    Files
  • marjerison_thesis.pdf

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