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Global-Local Mixtures: A Unifying Framework


Global-local mixtures, including Gaussian scale mixtures, have gained prominence in recent times, both as a sparsity inducing prior in pn problems as well as default priors for non-linear many-to-one functionals of high-dimensional parameters. Here we propose a unifying framework for global-local scale mixtures using the Cauchy-Schlömilch and Liouville integral transformation identities, and use the framework to build a new Bayesian sparse signal recovery method. This new method is a Bayesian counterpart of the \(\sqrt {\text {Lasso}}\) (Belloni et al., Biometrika 98, 4, 791–806, 2011) that adapts to unknown error variance. Our framework also characterizes well-known scale mixture distributions including the Laplace density used in Bayesian Lasso, logit and quantile via a single integral identity. Finally, we derive a few convolutions that commonly arise in Bayesian inference and posit a conjecture concerning bridge and uniform correlation mixtures.

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The horseshoe prior and the framework of global-local shrinkage priors were introduced in 2010 by a series of papers (Carvalho et al. 2010; Polson and Scott, 2010a), and around the same time, the framework of Bayes oracle for testing was introduced by Bogdan et al. (2011). The subject of Bayesian shrinkage, model selection and multiple testing almost immediately had an explosive development that is still going on. Besides playing a vital role in shaping the early history and the subsequent course of Bayesian theory and methodology, Professor Jayanta K. Ghosh contributed seminal theoretical results in the early history of Bayesian sparse signal recovery. We have written this paper to honor his memory.

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Correspondence to Jyotishka Datta.

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Bhadra and Polson are supported by Grant no. DMS-1613063 by the US National Science Foundation.

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Bhadra, A., Datta, J., Polson, N.G. et al. Global-Local Mixtures: A Unifying Framework. Sankhya A 82, 426–447 (2020).

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  • Bayes regularization
  • \(\sqrt {\text {Lasso}}\)
  • Convolution
  • Lasso
  • Logistic
  • Quantile

AMS (2000) subject classification

  • Primary 62F15
  • Secondary 62J07, 62C10