Modeling Latent Information in Voting Data with Dirichlet Process Priors

2015 ◽  
Vol 23 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Richard Traunmüller ◽  
Andreas Murr ◽  
Jeff Gill
Keyword(s):  
Dirichlet Process ◽  
Unobserved Heterogeneity ◽  
Vote Choice ◽  
Dirichlet Process Mixture ◽  
Omitted Variables ◽  
Factors Affecting ◽  
Structural Integration ◽  
Mixture Prior ◽  
Latent Effects ◽  
Improved Model

We apply a specialized Bayesian method that helps us deal with the methodological challenge of unobserved heterogeneity among immigrant voters. Our approach is based ongeneralized linear mixed Dirichlet models(GLMDMs) where random effects are specified semiparametrically using a Dirichlet process mixture prior that has been shown to account for unobserved grouping in the data. Such models are drawn from Bayesian nonparametrics to help overcome objections handling latent effects with strongly informed prior distributions. Using 2009 German voting data of immigrants, we show that for difficult problems of missing key covariates and unexplained heterogeneity this approach provides (1) overall improved model fit, (2) smaller standard errors on average, and (3) less bias from omitted variables. As a result, the GLMDM changed our substantive understanding of the factors affecting immigrants' turnout and vote choice. Once we account for unobserved heterogeneity among immigrant voters, whether a voter belongs to the first immigrant generation or not is much less important than the extant literature suggests. When looking at vote choice, we also found that an immigrant's degree of structural integration does not affect the vote in favor of the CDU/CSU, a party that is traditionally associated with restrictive immigration policy.

Bayesian Hierarchical Growth Model for Experimental Data on the Effectiveness of an Incentive-Based Weight Reduction Method

2021 ◽  
Vol 12 (3) ◽  
pp. 1036-1047
Author(s):  
Md Azman Shahadan Et.al
Keyword(s):  
Growth Model ◽  
Weight Reduction ◽  
Dirichlet Process ◽  
Reduction Method ◽  
Growth Models ◽  
Dirichlet Process Mixture ◽  
Bayesian Hierarchical ◽  
Mixture Prior ◽  
Hierarchical Growth Model ◽  
Hierarchical Growth Models

The objective of this current research is to model the experimental data on the effectiveness of an incentive-based weight reduction method by using Bayesian hierarchical growth models. Three Bayesian hierarchical growth models are proposed, namely parametric Bayesian hierarchical growth model with correlated intercept and slope random effects model, parametric Bayesian hierarchical growth model with no correlated intercept and slope random effects model and semi-parametric Bayesian hierarchical growth model with Dirichlet process mixture prior model. The data is obtained from forty eight (48) students who had participated in an experiment on weight reduction method. The students were divided equally into two groups: single and pair groups. The experiment was carried out over the period of three months with a weight reading session for every two weeks.  At the end of the study, we had six repeated measures of each student’s weight in kg and some measures of covariates and factors.  Our results showed that the best model for the above data based on the Bayesian fit indexes and the models’ flexibility is the semi-parametric Bayesian hierarchical growth model with Dirichlet process mixture prior model. The results of the semi-parametric model showed that the ‘growth’ or reduction rates of the weight reduction experiment relate to the students’ gender, height in cm, experimental group (single or pair) and time in term of weeks.

Use of Bivariate Dirichlet Process Mixture Spatial Model to Estimate Active Transportation-Related Crash Counts

2018 ◽  
Vol 2672 (38) ◽  
pp. 105-115 ◽  
Author(s):  
Wen Cheng ◽  
Gurdiljot Singh Gill ◽  
Tom Vo ◽  
Jiao Zhou ◽  
Taha Sakrani
Keyword(s):  
Dirichlet Process ◽  
Spatial Model ◽  
Unobserved Heterogeneity ◽  
Random Effect ◽  
Evaluation Criteria ◽  
Active Transportation ◽  
Parametric Models ◽  
Dirichlet Process Mixture ◽  
Pedestrian Crashes ◽  
The Impact

The current paper presents the comprehensive analysis of a bivariate Dirichlet process mixture spatial model for estimation of pedestrian and bicycle crash counts. This study focuses on active transportation at traffic analysis zone (TAZ) level by developing a semi-parametric model that accounts for the unobserved heterogeneity by combining the strengths of bivariate specification for correlation among crash modes; spatial random effects for the impact of neighboring TAZs; and Dirichlet process mixture for random intercept. Three alternate models, one Dirichlet and two parametric, are also developed for comparison based on different criteria. Bicycle and pedestrian crashes are observed to share three influential variables: the positive correlation of K12 student enrollment; the bike-lane density; and the percentage of arterial roads. The heterogeneity error term demonstrates the presence of statistically significant correlation among the bicycle and pedestrian crashes, whereas the spatial random effect term indicates the absence of a significant correlation for the area under focus. The Dirichlet models are consistently superior to non-Dirichlet ones under all evaluation criteria. Moreover, the Dirichlet models exhibit the capability to identify latent distinct subpopulations and suggest that the normal assumption of intercept associated with traditional parametric models does not hold true for the TAZ-level crash dataset of the current study.

scholarly journals 0439 Nonlinear Dynamics Forecasting for Personalize Prognosis of Obstructive Sleep Apnea Onsets

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A168-A169
Author(s):  
T Le
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Real Time ◽  
Dirichlet Process ◽  
Clinical Symptoms ◽  
Risk Indicators ◽  
Dirichlet Process Mixture ◽  
Obstructive Sleep ◽  
Estimated Risk ◽  
Normal States

Abstract Introduction The emphasis on disease prevention, early detection, and preventive treatments will revolutionize the way sleep clinicians evaluate their patients. Obstructive Sleep Apnea (OSA) is one of the most prevalent sleep disorders with approximately 100 millions patients been diagnosed worldwide. The effectiveness of sleep disorder therapies can be enhanced by providing personalized and real-time prediction of OSA episode onsets. Previous attempts at OSA prediction are limited to capturing the nonlinear, nonstationary dynamics of the underlying physiological processes. Methods This paper reports an investigation into heart rate dynamics aiming to predict in real time the onsets of OSA episode before the clinical symptoms appear. The method includes (a) a representation of a transition state space network to characterize dynamic transition of apneic states (b) a Dirichlet-Process Mixture-Gaussian-Process prognostic method for estimating the distribution of the time estimate the remaining time until the onset of an impending OSA episode by considering the stochastic evolution of the normal states to an anomalous (apnea) Results The approach was tested using three datasets including (1) 20 records from 14 OSA subjects in benchmark ECG apnea databases (Physionet.org), (2) records of eight subjects from previous work. The average prediction accuracy (R2) is reported as 0.75%, with 87% of observations within the 95% confidence interval. Estimated risk indicators at 1 to 3 min till apnea onset are reported as 85.8 %, 80.2 %, and 75.5 %, respectively. Conclusion The present prognosis approach can be integrated with wearable devices to facilitate individualized treatments and timely prevention therapies. Support N/A

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