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A Generalized Additive Model approach to evaluating water quality: Chesapeake Bay case study
Nutrient reduction efforts have been undertaken in recent decades to mitigate the impacts of eutrophication in coastal and estuarine systems worldwide. To track progress in response to one of these efforts we use Generalized Additive Models (GAMs) to evaluate a diverse suite of water quality constituents over a 32-year period in the Chesapeake Bay, an estuary on the east coast of the United States. Model development included selecting a GAM structure to describe nonlinear seasonally-varying changes over time, incorporating hydrologic variability via either river flow or salinity, and using interventions to model method or laboratory changes suspected to impact data. This approach, transferable to other systems, allows for evaluation of water quality data in a statistically rigorous way, while being suitable for application to many sites and variables. This enables consistent generation of annual updates, while providing a tool for developing insights to a range of management- and research- focused questions.
Keywords: Generalized Additive Models, Water quality, Chesapeake Bay, Trend analysis
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A case study on using generalized additive models to fit credit rating scores Marlene Müller, [email protected] This version: July 8, 2009, 14:32. Contents ... credit data case study: 4 credit datasets regressors dataset sample defaults continuous discrete categorical German Credit 1000 30.00% 3 - 17
standard tools to estimate generalized additive models: the function gam::gamimplements backfit-ting with local scoring (Hastie and Tibshirani; 1990) and the function mgcv::gamimplements penalized regression splines (Wood; 2006). This study compares these two procedures under their default settings. Case Study Setup Altogether, we consider the ...
In this case study, with a large number of analyses to conduct every year, we needed to select a reasonable default k-value. After some testing, it was clear that many of the nonlinear patterns over time are due to multi-year wet and dry periods. ... Using generalized additive models for water quality assessments: a case study example from ...
Using generalized additive models for water quality assessments: A case study example from Australia 111 ... The case study is based upon an extensive water quality monitoring program that recently took place along the coastal region of the Gold Coast, Queensland, Australia. We use GAMs to uncover the
14 these efforts we use Generalized Additive Models (GAMs) to evaluate a diverse suite of water quality 15 constituents over a 32-year period in the Chesapeake Bay, an estuary on the east coast of the United 16 States. Model development included selecting a GAM structure to describe nonlinear seasonally-varying
Meanwhile R comprises a number of different packages to fit generalized additive models. In this study we compare GAM estimating approaches with a focus on the specific structure of credit data: small default rates, mixed discrete and continuous explanatory variables, possibly nonlinear dependencies between the regressors. ... A case study on ...
underlying the generalized additive model. We then present a worked example of how GAMs can be used to obtain a thorough understanding of the quantitative structure of linguistic data. 2.1 The generalized linear model Central to the generalized linear model is the idea that a response variable Y ifor a datapoint ithat is described by ...
As an alternative to this two-step approach, generalized additive models (GAM) would allow for a simultaneous estimation of both the initial transformation and final logit fit. In this study we compare GAM estimating approaches with a focus on the specific structure of credit data: small default rates, mixed discrete and continuous explanatory ...
To track progress in response to one of these efforts we use Generalized Additive Models (GAMs) to evaluate a diverse suite of water quality constituents over a 32-year period in the Chesapeake Bay, an estuary on the east coast of the United States ... Chesapeake Bay Case Study: DOI: 10.1016/j.envsoft.2019.03.027: Authors: Rebecca Murphy, Elgin ...
A Generalized Additive Model approach to evaluating water quality: Chesapeake Bay case study. ... To track progress in response to one of these efforts we use Generalized Additive Models (GAMs) to evaluate a diverse suite of water quality constituents over a 32-year period in the Chesapeake Bay, an estuary on the east coast of the United States