# Updated: Formulas for Bayesian A/B Testing

DevFeed: [Updated: Formulas for Bayesian A/B Testing](<https://devfeed.tech/articles/updated-formulas-for-bayesian-a-b-testing-37884.md>)

Original publisher: [Read original article](<https://www.evanmiller.org/bayesian-ab-testing.html>)

Author: Evan Miller

Published: 2020-04-08T11:15:00Z

Content type: tutorial

Language: en

Sources: [Evan Miller](<https://devfeed.tech/sources/evan-miller.md>)

Topics: [A/B Testing](<https://devfeed.tech/topics/a-b-testing.md>), [math](<https://devfeed.tech/topics/math.md>)

Tags: [a-b-testing](<https://devfeed.tech/tags/a-b-testing.md>), [math](<https://devfeed.tech/tags/math.md>), [test](<https://devfeed.tech/tags/test.md>)

## AI overview

This article presents closed-form formulas for evaluating Bayesian A/B tests, including the probability that one variant will outperform another in the long run. It covers binary outcomes, beta distributions, derivation, and implementation considerations.

## Source excerpt

I've updated Formulas for Bayesian A/B Testing to include a new equation for analyzing four-pronged (A/B/C/D) tests.