Threshold knot selection for large-scale spatial models with applications to the Deepwater Horizon disaster |
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Authors: | Casey M Jelsema Richard K Kwok Shyamal D Peddada |
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Institution: | 1. Department of Biostatistics, School of Public Health, West Virginia University, Morgantown, WV, USA;2. Epidemiology Branch, National Institute of Environmental Health Sciences, NC, USA;3. Department of Biostatistics, School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA |
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Abstract: | Large spatial datasets are typically modelled through a small set of knot locations; often these locations are specified by the investigator by arbitrary criteria. Existing methods of estimating the locations of knots assume their number is known a priori, or are otherwise computationally intensive. We develop a computationally efficient method of estimating both the location and number of knots for spatial mixed effects models. Our proposed algorithm, Threshold Knot Selection (TKS), estimates knot locations by identifying clusters of large residuals and placing a knot in the centroid of those clusters. We conduct a simulation study showing TKS in relation to several comparable methods of estimating knot locations. Our case study utilizes data of particulate matter concentrations collected during the course of the response and clean-up effort from the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. |
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Keywords: | Fixed rank kriging knot selection reduced rank spatial model spatial mixed effects |
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