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arXiv 1801.09299stat.COstat.ME
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吉布斯取样器The Gibbs Sampler

Adapting The Gibbs Sampler

Cyril Chimisov, Krzysztof Latuszynski, Gareth Roberts

摘要:

自适应MCMC的流行一方面是由于其在应用中的成功,另一方面是由于Metropolis算法接受率(以及等效的提案规模)的数学吸引力和计算上简单的优化标准。迄今为止,还没有设计出用于优化随机扫描吉布斯采样器的选择概率的类似的原则和操作标准。在目前的工作中,我们关闭这一差距,并开发了一个通用的自适应随机扫描吉布斯采样器,适应选择概率。自适应是通过优化目标的高斯模拟的$L_2-$光谱间隙来引导的,逐渐地,因为目标的全局协方差是由采样器学习的。额外的计算成本的适应表示一小部分的总模拟工作。“我们提出了一些中等和高维的例子,包括截断高斯,贝叶斯层次模型和隐马尔可夫模型,其中显着的计算增益都是经验性观察,自适应吉布斯,自适应大都会内的自适应吉布斯版本的算法。我们认为,自适应随机扫描吉布斯采样器可以定期实施和大量的计算增益将观察到许多典型的吉布斯抽样问题。我们将给出自适应算法的遍历性可以成立的条件。

英文摘要:

The popularity of Adaptive MCMC has been fueled on the one hand by its success in applications, and on the other hand, by mathematically appealing and computationally straightforward optimisation criteria for the Metropolis algorithm acceptance rate (and, equivalently, proposal scale). Similarly principled and operational criteria for optimising the selection probabilities of the Random Scan Gibbs Sampler have not been devised to date. In the present work, we close this gap and develop a general purpose Adaptive Random Scan Gibbs Sampler that adapts the selection probabilities. The adaptation is guided by optimising the $L_2-$spectral gap for the target's Gaussian analogue, gradually, as target's global covariance is learned by the sampler. The additional computational cost of the adaptation represents a small fraction of the total simulation effort. ` We present a number of moderately- and high-dimensional examples, including truncated Gaussians, Bayesian Hierarchical Models and Hidden Markov Models, where significant computational gains are empirically observed for both, Adaptive Gibbs, and Adaptive Metropolis within Adaptive Gibbs version of the algorithm. We argue that Adaptive Random Scan Gibbs Samplers can be routinely implemented and substantial computational gains will be observed across many typical Gibbs sampling problems. We shall give conditions under which ergodicity of the adaptive algorithms can be established.

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