The analysis of threshold models with fixed and random effects and associated variance components is discussed from the perspective of generalizedlinear mixed models (GLMMs). Parameters are estimated by an interative...
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The analysis of threshold models with fixed and random effects and associated variance components is discussed from the perspective of generalizedlinear mixed models (GLMMs). Parameters are estimated by an interative procedure, referred to as iterated re-weighted REML (IRREML). This procedure is an extension of the iterative re-weighted least squares algorithm for generalized linear models. An advantage of this approach is that it immediately suggests how to extend ordinary mixed-model methodology to GLMMs. This is illustrated for lambing difficulty data. IRREML can be implemented with standard software available for ordinary normal data mixed models. The connection with other estimation procedures, eg, the maximum a posteriori (MAP) approach, is discussed. A comparison by simulation with a related approach shows a distinct pattern of the bias of MAP and IRREML for heritability. When the number of fixed effects is reduced, while the total number of observations is kept about the same, bias decreases from a large positive to a large negative value, seemingly independently of the sizes of the fixed effects.
Methods for generalized linear models are extended to provide estimates of location and variance parameters for mixed models fitted to binomial data formed by classifying samples from an underlying normal distribution...
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Methods for generalized linear models are extended to provide estimates of location and variance parameters for mixed models fitted to binomial data formed by classifying samples from an underlying normal distribution. The method estimates the parameters directly on the underlying scale. For a balanced one-way random effects model, the variance estimator simplifies to the usual analysis of variance one. The estimation of variances and the prediction of random effects for binomial traits is required by animal breeders. The predictors given are analogous to best linear unbiased predictors (Henderson, 1973) but differ from those presented by Harville and Mee (1984).
We developed a hierarchical Bayesian generalized linear model (Delta model) for CPUE standardization and tested this model with Japanese longline fisheries data from 1975 to 2006 for south Pacific Ocean albacore tuna ...
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We developed a hierarchical Bayesian generalized linear model (Delta model) for CPUE standardization and tested this model with Japanese longline fisheries data from 1975 to 2006 for south Pacific Ocean albacore tuna (Thunnus alalunga) The Delta model consists of binomial and lognormal sub-models and was developed to predict catch rates for areas bypassed by the fishery in some years Incorporation of these predicted catch rates into the standardization process mitigates the impact of spatial contractions in fishing pattern on the estimation of abundance indices The relative abundance of albacore as measured by the standardized and nominal CPUEs are similar for the early years when the spatial pattern of the fishing did not change However when the spatial coverage of fishing was decreasing the standardized CPUEs without predicted catch rates and nominal CPUEs were similar in the first half of this period but the standardized CPUE was lower than nominal CPUE in the remaining years of this period In contrast standardized CPUEs with the inclusion of predicted catch rates indicated significantly lower abundances than the nominal CPUEs for this entire period Explanatory variables considered in this study were Year Month Area Year-Area interaction and Depth using hooks per basket (HPB) as a proxy variable All variables except for HPB were important in explaining variations in catch rates Comparison of model predicted probabilities and observed proportions of non-zero catches showed that the binomial sub-model fit was adequate and calculated Bayesian p-values indicated that the lognormal sub-model fit was acceptable We also show that model fitting can be improved by adding random process error into the relationship between the explanatory variables and the function of the expected values of the response variables Crown Copyright (C) 2010 Published by Elsevier B V All rights reserved
When faced with a binary or count outcome, informative hypotheses can be tested in the generalized linear model using the distance statistic as well as modified versions of the Wald, the Score and the likelihood-ratio...
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When faced with a binary or count outcome, informative hypotheses can be tested in the generalized linear model using the distance statistic as well as modified versions of the Wald, the Score and the likelihood-ratio test (LRT). In contrast to classical null hypothesis testing, informative hypotheses allow to directly examine the direction or the order of the regression coefficients. Since knowledge about the practical performance of informative test statistics is missing in the theoretically oriented literature, we aim at closing this gap using simulation studies in the context of logistic and Poisson regression. We examine the effect of the number of constraints as well as the sample size on type I error rates when the hypothesis of interest can be expressed as a linear function of the regression parameters. The LRT shows the best performance in general, followed by the Score test. Furthermore, both the sample size and especially the number of constraints impact the type I error rates considerably more in logistic compared to Poisson regression. We provide an empirical data example together with R code that can be easily adapted by applied researchers. Moreover, we discuss informative hypothesis testing about effects of interest, which are a non-linear function of the regression parameters. We demonstrate this by means of a second empirical data example.
We propose a generalized partially linear functional single index risk score model for repeatedly measured outcomes where the index itself is a function of time. We fuse the nonparametric kernel method and regression ...
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We propose a generalized partially linear functional single index risk score model for repeatedly measured outcomes where the index itself is a function of time. We fuse the nonparametric kernel method and regression spline method, and modify the generalized estimating equation to facilitate estimation and inference. We use local smoothing kernel to estimate the unspecified coefficient functions of time, and use B-splines to estimate the unspecified function of the single index component. The covariance structure is taken into account via a working model, which provides valid estimation and inference procedure whether or not it captures the true covariance. The estimation method is applicable to both continuous and discrete outcomes. We derive large sample properties of the estimation procedure and show a different convergence rate for each component of the model. The asymptotic properties when the kernel and regression spline methods are combined in a nested fashion has not been studied prior to this work, even in the independent data case.
Diagnosis of most ophthalmic conditions, such as diabetic retinopathy, generally relies on an effective analysis of retinal blood vessels. Techniques that depend solely on the visual observation of clinicians can be t...
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Evapotranspiration is a key variable of the water cycle. Its calculation requires several ground data that frequently are not available. This study contains a detailed method and measurements of meteorological and ene...
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Evapotranspiration is a key variable of the water cycle. Its calculation requires several ground data that frequently are not available. This study contains a detailed method and measurements of meteorological and energy balance variables that can be used to estimate the daily actual evapotranspiration (ETa). A lineargeneralizedmodel is obtained to calculate the ETa from common variables measured in meteorological stations. The method showed a good performance over a barley crop of easthern Argentine Pampas and can be applied and tested in other great plains. Measurements of soil-plant-atmosphere are included The routines to reproduce the method are included The generalized method allows the calculation of daily ETa over crops and was tested over barley crops (c) 2022 Published by Elsevier B.V. This is an open access article under the CC BY license ( http://***/licenses/by/4.0/ )
This article documents the application of the Poisson inverse Gaussian (PIG) regression model for modeling motor vehicle crash data. The PIG distribution, which mixes the Poisson distribution and inverse Gaussian dist...
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This article documents the application of the Poisson inverse Gaussian (PIG) regression model for modeling motor vehicle crash data. The PIG distribution, which mixes the Poisson distribution and inverse Gaussian distribution, has the potential for modeling highly dispersed count data due to the flexibility of inverse Gaussian distribution. The objectives of this article were to evaluate the application of PIG regression model for analyzing motor vehicle crash data and compare the results with negative binomial (NB) model, especially when varying dispersion parameter is introduced. To accomplish these objectives, NB and PIG models were developed with fixed and varying dispersion parameters and compared using two data sets. The results of this study show that PIG models perform better than the NB models in terms of goodness-of-fit statistics. Moreover, the PIG model can perform as well as the NB model in capturing the variance of crash data. Lastly, PIG models demonstrate almost the same prediction performance compared to NB models. Considering the simple form of PIG model and its easiness of applications, PIG model could be used as a potential alternative to the NB model for analyzing crash data.
Dengue fever is a global life-threatening vector-borne disease which is mainly distributed by the vector Aedes Aegypti mosquito. It is known that the development and survivorship of this vector depends on surrounding ...
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ISBN:
(纸本)9789811673344;9789811673337
Dengue fever is a global life-threatening vector-borne disease which is mainly distributed by the vector Aedes Aegypti mosquito. It is known that the development and survivorship of this vector depends on surrounding climate. The dengue outbreak in Kelantan, Malaysia is alarming. The aim of the study was to compare the fixed effects Negative Binomial GLM and Bayesian Poisson GLMM in prediction of dengue incidence in Kelantan. The data involved daily number of reported dengue cases (1st January 2013-31st December 2017) in ten districts of Kelantan which was collected from Ministry of Health Malaysia. The climate variables, average daily temperature, relative humidity and rainfall (climatic data) were obtained from NASA's Global Climate Change website, while the population data were from Department of Statistics Malaysia. Statistical modeling results revealed that the fixed effects Negative Binomial GLM failed to fit the daily dengue incidence when serious epidemic occurred. The spatio-temporal Bayesian Poisson GLMM model improved the prediction of dengue incidence. Relative humidity at lag 7 days and 21 days and average temperature at lag 21 days were found to be significant contributing factors of dengue incidence in Kelantan. The findings of the study are significant to respective local authorities in providing vital information for early dengue warning systems in a particular area. This is important for authorities to monitor and reduce dengue incidence in endemic areas and to safeguard the community from dengue outbreak.
OBJECTIVE: To investigate the use of the Gibbs-Sampler method in evaluating the relationship between clinic events and health risks in a meta-analysis of multiple clinical trials. METHODS: By using a generalized linea...
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OBJECTIVE: To investigate the use of the Gibbs-Sampler method in evaluating the relationship between clinic events and health risks in a meta-analysis of multiple clinical trials. METHODS: By using a generalized linear model with random-effects, Gibbs-Sampler technique was used in a meta-analysis of multiple clinical trials of angiotensin converting enzyme (ACE) inhibitors in patients with myocardial infarction (MI). RESULTS: When heterogeneity across different trials can not be ignored, compared with the classic method, the odds ratio of relative reinfarction risk estimated by the Gibbs-Sampler method would have less variation. The gain in the reduction of variation in estimate of the overall odds ratio was 9.52%. CONCLUSION: Implementation of the Gibbs-Sampler technique in meta-analysis of multiple clinical trials has the potential of reducing the inaccuracy caused by heterogeneity across trials.
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