[GTM glossary](/glossary.txt) A/B testing

Marketing

# A/B testing

Also known as: split testing, A/B test

In short

A/B testing is a controlled experiment in which two versions of one asset, such as a landing page, email subject line, or ad, are shown to similar audiences at the same time. The version that performs better on a pre-chosen metric wins.

For B2B teams the method is useful but limited by volume. Many B2B pages get modest traffic, so tests need a clear hypothesis, a single change, and enough visitors to tell a real difference from noise.

## How to run an A/B test

### 1. Pick one metric and one change

Decide the primary metric first, for example demo-request rate on a landing page. Change only one element, such as the headline, so you know what caused any difference.

### 2. Split traffic randomly

Send half of visitors to version A and half to version B at the same time. Running A in one week and B in the next mixes in seasonal and campaign effects.

### 3. Wait for enough data

Stopping the moment one version leads is the most common error. Set a sample size or a minimum run time before you start, and keep to it.

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## What B2B teams can test

* **Email:** Subject lines, opening sentences, call to action, and send time.
* **Landing pages:** Headlines, form length, proof points, and button text.
* **Ads:** Creative, copy, and audience targeting.
* **Outbound:** Message angles and value propositions across similar lists of accounts.

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## Example

Say a team sends 1,000 emails with subject line A and 1,000 with subject line B to comparable accounts. If reply rates are close, the team has learned that the subject line does not matter much, and should test something with more leverage, such as the offer.

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## Common mistakes

* **Testing too many things:** Changing the headline, image, and form at once hides which change worked.
* **Too little traffic:** Small samples produce differences that disappear when repeated.
* **Optimizing a shallow metric:** A version that wins on clicks but loses on qualified pipeline is not a win.
* **Not recording results:** Keep a log of hypotheses and outcomes so the team does not repeat old tests.

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## A/B testing FAQs

**What is A/B testing in marketing?**

A/B testing is an experiment that shows two versions of an asset, such as an email or landing page, to similar audiences at the same time. You then compare results on one chosen metric to learn which version performs better.

**How long should an A/B test run?**

Run it until you reach the sample size you set before starting, and long enough to cover a full business cycle, often at least one to two weeks. Ending early when one version looks ahead tends to produce false winners.

**Can you do A/B testing with low B2B traffic?**

Yes, but pick high-impact changes and bigger audiences. Email and outbound tests often reach useful volume faster than web pages. With low traffic, test bold changes such as the offer rather than small tweaks like button color.

**What is the difference between A/B testing and multivariate testing?**

A/B testing compares two versions that differ in one element. Multivariate testing changes several elements at once and measures every combination, which needs much more traffic. Most B2B teams get more value from simple A/B tests.

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## More related phrases

* [Incrementality](/glossary/incrementality.txt)
* [User experience](/glossary/user-experience.txt)
* [Landing pages](/glossary/landing-pages.txt)

## Similar phrases

* [Conversion rate optimization (CRO)](/glossary/conversion-rate-optimization.txt)  
Conversion rate optimization (CRO) is the practice of improving the share of visitors who take a desired action, using research and controlled tests.
* [Marketing testing](/glossary/marketing-testing.txt)  
Marketing testing is the practice of running structured experiments on messages, offers, channels, and audiences to learn what improves results before scaling spend or changing strategy.
* [Content marketing](/glossary/content-marketing.txt)  
Content marketing is the practice of creating and sharing useful content, such as articles, guides, and videos, to attract, educate, and convert a defined audience.
* [Above the fold](/glossary/above-the-fold.txt)  
Above the fold is the part of a web page visible without scrolling, and it decides whether a visitor stays, reads on, or leaves within seconds.
* [Conversion rate](/glossary/conversion-rate.txt)  
Conversion rate is the percentage of people or accounts that move from one stage of your funnel to the next, and it shows where your go-to-market motion leaks.