Question 1

What is prompt A/B testing?

Accepted Answer

Prompt A/B testing runs two versions of a prompt through the same AI model under the same conditions, then compares the two outputs against criteria you choose. It replaces the usual "this one feels better" judgement with a like-for-like comparison you can actually point at.

Question 2

What is an AI judge, and can you trust it?

Accepted Answer

An AI judge is a second model whose only job is to score the two outputs against your criteria and explain its choice. It is useful because it is consistent and fast, but it is not infallible: judges can favour longer or more confident-sounding answers. PromptVibe reduces the best-known bias by showing the judge the two outputs in a random order and mapping the verdict back afterwards, and it always shows you both outputs so you can overrule it.

Question 3

Why use a different model as the judge?

Accepted Answer

Asking the model that wrote an answer to grade that answer is a self-assessment, not an evaluation. PromptVibe always judges with a different model from the one being tested, so the score comes from somewhere other than the thing being scored.

Question 4

What should I change between version A and version B?

Accepted Answer

Change one thing at a time. If A and B differ in role, length, tone and format all at once, a win tells you nothing about which change caused it. Test one variable per run — add a role, or specify a format, or add a constraint — and keep the winner as the new baseline for the next test.

Prompt A/B Testing

What should the judge care about?

Your verdict appears here