Decoder. plain-English AI glossary

A/B Test

● Core

Randomly split users into two groups: one gets version A, one gets version B, then you measure which one wins.

Think of it like

Like a restaurant trying two recipes and seeing which one customers prefer.

Example

Half of users get prompted with 'How can I help?' the other half with 'What do you need?' You measure which phrasing leads to more productive conversations.

How it actually works

A/B testing is the gold standard for measuring real-world impact because it controls for confounds. You're measuring the effect of one change in isolation. The catch: you need enough traffic to detect differences, you need to avoid peeking, and multiple hypothesis testing can fool you. Also, not every decision should be A/B tested (some are too costly, others are clearly better).

For product teams

Run A/B tests before major launches to de-risk decisions and measure real user impact.

For engineers

Implement randomization, logging, and analysis infrastructure; plan sample size before running.

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