How to Run an A/B Test on Google Ads

In Google Ads, you can run A/B tests to measure the impact of changing one or more variables in a campaign.

Here's how, step by step:

Start by defining the goal of your A/B test and the variable you want to test. We recommend testing one variable at a time so you can accurately measure its impact.

Note that you can run different types of tests: ad tests, custom tests for Display campaigns and Search Network campaigns, as well as video tests.

For this example, we'll run a custom test on a Search Network campaign, specifically on the bidding strategy.

In your Google Ads account, go to the "Drafts & Experiments" tab in the left sidebar, then create a draft campaign by clicking "+". You'll need to:

1) Select the campaign you want to test. If you're choosing a target CPA campaign, go with one that has more than 60 conversions per month. For target ROAS campaigns, choose one with more than 100 conversions per month.

2) Name your draft campaign. When naming it, make sure to use a different name from your source campaign to make it easier to read the results.

Once your draft campaign is created, make the change to the variable you want to test. Here, we'll update the bidding strategy in the settings.

Your draft campaign is ready and the changes are in place. Now go to the "Campaign Experiments" tab, click "+", and select your draft. At this step, you need to:

1) Choose the start and end date for the test. We recommend running tests for at least 8 weeks to account for the learning phase, the A/B test run itself, and the conversion lag.

2) Choose what percentage of your source campaign's budget to allocate to your test campaign. Ideally, split it 50/50 so the results aren't skewed by a budget difference.

3) Choose whether to base your test on cookies or on searches. With a cookie-based test, a user will only see ads from one campaign, regardless of how many times they search. With a search-based test, a user may see ads from both the source campaign and the test campaign.

5. Analyze your results. If the test is conclusive and your test campaign outperforms the original, you have two options:

1) Apply your test to your original campaign. The changes made in the test campaign will automatically be applied to the source campaign.

2) Create a new campaign based on the test, while keeping the source campaign running.

⚠️ Google has announced an upcoming change to how tests are created. It will be possible to create a test without going through the draft campaign step. You'll be able to create a test using a single workflow, in a tab called "Experiments".

Want expert support on Google Ads, or your broader digital marketing strategy? Don't hesitate to reach out!