نتایج جستجو برای: cluster sampling

تعداد نتایج: 402542  

2013
Jason Chang John W. Fisher

We present an MCMC sampler for Dirichlet process mixture models that can be parallelized to achieve significant computational gains. We combine a nonergodic, restricted Gibbs iteration with split/merge proposals in a manner that produces an ergodic Markov chain. Each cluster is augmented with two subclusters to construct likely split moves. Unlike some previous parallel samplers, the proposed s...

Journal: :JAMDS 2007
Alastair Scott Chris Wild

We look at fitting regression models using data from stratified cluster samples when the strata may depend in some way on the observed responses within clusters. One important subclass of examples is that of family studies in genetic epidemiology, where the probability of selecting a family into the study depends on the incidence of disease within the family. We develop the survey-weighted esti...

Journal: :CoRR 2016
Ahmed Attia Azam S. Zavar Moosavi Adrian Sandu

This paper presents a fully non-Gaussian version of the Hamiltonian Monte Carlo (HMC) sampling filter. The Gaussian prior assumption in the original HMC filter is relaxed. Specifically, a clustering step is introduced after the forecast phase of the filter, and the prior density function is estimated by fitting a Gaussian Mixture Model (GMM) to the prior ensemble. Using the data likelihood func...

2014
Jason Chang John W. Fisher

We develop a sampling technique for Hierarchical Dirichlet process models. The parallel algorithm builds upon [1] by proposing large split and merge moves based on learned sub-clusters. The additional global split and merge moves drastically improve convergence in the experimental results. Furthermore, we discover that cross-validation techniques do not adequately determine convergence, and tha...

2007
Alastair Scott Chris Wild

We look at fitting regression models using data from stratified cluster samples when the strata may depend in some way on the observed responses within clusters. One important subclass of examples is that of family studies in genetic epidemiology, where the probability of selecting a family into the study depends on the incidence of disease within the family. We develop the survey-weighted esti...

2016
Melike Oguz-Alper Yves G. Berger

The data used in social, behavioural, health or biological sciences may have a hierarchical structure due to the natural structure in the population of interest or due to the sampling design. Multilevel or marginal models are often used to analyse such hierarchical data. The data may include sample units selected with unequal probabilities from a clustered and stratified population. Inferences ...

Journal: :CoRR 2017
Farshid Rayhan Sajid Ahmed Asif Mahbub Md. Rafsan Jani Swakkhar Shatabda Dewan Md. Farid

Class imbalance classification is a challenging research problem in data mining and machine learning, as most of the real-life datasets are often imbalanced in nature. Existing learning algorithms maximise the classification accuracy by correctly classifying the majority class, but misclassify the minority class. However, the minority class instances are representing the concept with greater in...

2010
Jake Porway Song-Chun Zhu

This paper presents a novel Markov Chain Monte Carlo (MCMC) inference algorithm called C4 – Clustering with Cooperative and Competitive Constraints for computing multiple solutions from posterior probabilities defined on graphical models, including Markov random fields (MRF), conditional random fields (CRF) and hierarchical models. The graphs may have both positive and negative edges for cooper...

Journal: :Statistical Methods and Applications 2011
Stefano Antonio Gattone Tonio Di Battista

The adaptive cluster sampling (ACS) is a suitable sampling design for rare and clustered populations. In environmental and ecological applications, biological populations are generally animals or plants with highly patchy spatial distribution. However, ACS would be a less efficient design when the study population is not rare with low aggregation since the final sample size could be easily out ...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2002
Martin Weigel Wolfhard Janke Chin-Kun Hu

Using the random-cluster representation of the q-state Potts models we consider the pooling of data from cluster-update Monte Carlo simulations for different thermal couplings K and number of states per spin q. Proper combination of histograms allows for the evaluation of thermal averages in a broad range of K and q values, including noninteger values of q. Due to restrictions in the sampling p...

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