Many thanks to Gregory Gundersen for the blog theme.

Combining Samples From Non-mixing MCMC Chains

Regularized Least Squares with Singular Prior

Solving the regularized least squares optimization problem when the prior covariance matrix is not positive definite.

Markov Melding

Combining and splitting models in a Bayesian framework.

Ensemble Kalman Methodology for Inverse Problems

Particle-based Kalman methods for the approximate solution of Bayesian inverse problems.

Pseudo-Marginal MCMC

Motivated by Bayesian inference, I introduce the pseudo-marginal approach to MCMC and then discuss why is works from a more generic perspective.

Probabilistic Forecasting and Calibration

The Ensemble Kalman Filter

I introduce the ensemble Kalman filter as a Monte Carlo approximation to the Kalman filter in the linear Gaussian state space setting, then discuss how is applied as an approximation even when these assumptions don't hold.

Linear Gaussian Inverse Problems

Derivations and discussion of linear Gaussian inverse problems.

The Polynomial Kernel

Introduction and basic properties, kernel ridge regression, Gaussian processes.

Basis Expansions for Black-Box Function Emulation

A discussion of the popular output dimensionality strategy for emulating multi-output functions.

A Few Different Adaptive Metropolis Schemes

Adaptively updating a Gaussian proposal covariance for Random Walk Metropolis-Hastings samplers.

Active Subspaces

An introduction to dimensionality reduction via active subspaces.

Gaussian Measures, Part 2 - The Multivariate Case

A fairly deep dive into Gaussian measures in finitely many dimensions. The next step in building up to the infinite-dimensional case.

Gaussian Measures, Part 1 - The Univariate Case

A brief introduction to Gaussian measures in one dimension, serving to provide the setup for an extension to multiple, and eventually infinite, dimensions.

An Introduction to Scattered Data Approximation

I summarize the first chapter of Holger Wendland's book "Scattered Data Approximation", which I augment with some background on polynomial interpolation and splines.

Generalizing the Outer Product to Hilbert Space

I briefly discuss how the outer product, familiar in Euclidean space, can be viewed as a linear operator which can readily be generalized to Hilbert space.

Gaussian Conditioning under Linear Transformations

I derive generalizations of the standard Gaussian conditioning identities whereby components of the Gaussian vector are subject to linear maps, and highlight applications to Gaussian processes.

Approximating Nonlinear Functions of Gaussians, Part I - Linearized Kalman Filter Extensions

I discuss the generic problem of approximating the distribution resulting from a non-linear transformation of a Gaussian random variable, and then show how this leads to extensions of the Kalman filter which yield approximate filtering algorithms in the non-linear setting.

The Kalman Filter

I discuss the Kalman filter from both the probabilistic and optimization perspectives, and provide multiple derivations of the Kalman update.

An Introduction to Bayesian Filtering and Smoothing

I provide an overview of the general framework for statistical filtering, viewed from the Bayesian perspective.

The Measure-Theoretic Context of Bayes' Rule

I describe Bayes' rule in a measure-theoretic context, explain how it can be viewed as a non-linear operator on probability measures, and detail applications to Bayesian inverse problems.

Gaussian Process Priors, Specification and Parameter Estimation

A deep dive into hyperparameter specifications for GP mean and covariance functions, including both frequentist and Bayesian methods for hyperparameter estimation.

Deriving the Metropolis-Hastings Update from the Transition Kernel

Given only the Metropolis-Hastings transition kernel, I show how to recover the Metropolis-Hastings update rule.

Principal Components Analysis

I derive the PCA decomposition from both a minimum reconstruction error and maximum variance perspective. I also discuss a statistical interpretation of PCA.