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TL;DR

A statistical framework that updates beliefs via Bayes' theorem: \( p(\theta|data) \propto p(data|\theta) p(\theta) \). The posterior combines prior knowledge with observed data through the likelihood.

By Valenke Exam Prep Team·Last updated 2026-06-03

Bayesian Inference

A statistical framework that updates beliefs via Bayes' theorem: \( p(\theta|data) \propto p(data|\theta) p(\theta) \). The posterior combines prior knowledge with observed data through the likelihood.

Why it matters for interviews

Bayesian methods are increasingly used in portfolio optimization (Black-Litterman), signal combination, and regime detection. They naturally incorporate uncertainty and prior knowledge, avoiding overfitting issues common in frequentist approaches.

Definition and Mathematical Foundation

A statistical framework that updates beliefs via Bayes' theorem: \( p(\theta|data) \propto p(data|\theta) p(\theta) \). The posterior combines prior knowledge with observed data through the likelihood.

Application in Quantitative Finance

Bayesian methods are increasingly used in portfolio optimization (Black-Litterman), signal combination, and regime detection. They naturally incorporate uncertainty and prior knowledge, avoiding overfitting issues common in frequentist approaches.

Related Concepts

Related Terms

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Frequently Asked Questions

What is the Black-Litterman model?
A Bayesian portfolio optimization framework. The prior is the market equilibrium (CAPM) portfolio. Investor views are incorporated as likelihood, producing a posterior that blends market consensus with personal views.
How does Bayesian inference handle small samples?
The prior regularizes estimates when data is scarce. As more data arrives, the posterior concentrates around the MLE. This graceful interpolation between prior knowledge and data is ideal for financial applications with limited history.
What is MCMC and why is it needed?
Markov Chain Monte Carlo generates samples from the posterior when analytical computation is intractable. Algorithms like Metropolis-Hastings and Hamiltonian Monte Carlo are used for complex models with many parameters.