Likelihood Maximization and Moment Matching in Low SNR Gaussian Mixture Models
- Courant Institute, New York, NY (United States)
- ETH Zurich (Switzerland)
We derive an asymptotic expansion for the log-likelihood of Gaussian mixture models (GMMs) with equal covariance matrices in the low signal-to-noise regime. The expansion reveals an intimate connection between two types of algorithms for parameter estimation: the method of moments and likelihood optimizing algorithms such as Expectation-Maximization (EM). We show that likelihood optimization in the low SNR regime reduces to a sequence of least squares optimization problems that match the moments of the estimate to the ground truth moments one by one. This connection is a stepping stone towards the analysis of EM and maximum likelihood estimation in a wide range of models. A motivating application for the study of low SNR mixture models is cryo-electron microscopy data, which can be modeled as a GMM with algebraic constraints imposed on the mixture centers. We discuss the application of our expansion to algebraically constrained GMMs, among other example models of interest. © 2022 The Authors. Communications on Pure and Applied Mathematics published by Wiley Periodicals LLC.
- Research Organization:
- Texas A & M University, College Station, TX (United States)
- Sponsoring Organization:
- USDOE; National Science Foundation (NSF)
- OSTI ID:
- 2424512
- Journal Information:
- Communications on Pure and Applied Mathematics, Journal Name: Communications on Pure and Applied Mathematics Journal Issue: 4 Vol. 76; ISSN 0010-3640
- Publisher:
- WileyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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