The Optimization tab

About experiments

Running an experiment allows you to compare one of your ad settings against a variation of that setting to see which performs better. Experiments work by splitting your site’s traffic between the original ad setting and the variation, so that their performance can be measured side by side. Experiments help you to make informed decisions about how to configure your ad settings, and can help you to increase your earnings.

Here are some examples of the types of experiments that you can run:

  • Compare the performance of text-only ad units to ad units that have both text and display enabled
  • Analyze the effect of changing the color of ad text on ad performance
  • Determine the impact on your revenue of using ad serving, sensitive and/or general category blocks.

There are two ways to create experiments. You can either:

Life of a typical experiment

A typical experiment that you design yourself, follows these steps:

1. Preparing for your experiment

Before you create your experiment it’s a good idea to decide exactly what you’d like to test in the experiment.

  • Ad unit settings: All ad type and text ad style settings are available for experiments. If there are multiple changes that you would like to try (e.g., change the text ad background color and increase the text font size), you may want to run two different experiments - first an experiment for the background color change and then an experiment for the font size change.

    Note that the following ad units are not eligible for use in experiments:

  • Allow & block ads: The following ad blocking settings are available for experiments:

  • Ad balance: You can compare your current ad fill rate against a different ad fill rate. Learn more about ad balance.

Note that there are some limitations on the number of experiments that you can have running at any one time:

  • You can only run one ad unit settings experiment per ad unit.
  • You can only run one "Allow & block ads" experiment at a time.
  • You can only run one "Ad balance" experiment at a time.
  • You may run all three types of experiment at the same time.

2. Creating your experiment

When you create an experiment you:

  • Select the original ad setting that you want to compare the experiment variation against.
  • Select which settings you’d like to change for the variation.
  • Choose whether you'd like Google to automatically apply the winning setting for you after your experiment has finished.
    Selecting this option can help save you time, for example, if you're planning to run lots of experiments.

The “create experiment” page guides you through each step, and provides you with more information. When you’re finished setting up your experiment, you can start it.

3. Monitoring your experiment

Once your experiment is up and running, it’s up to you to monitor its progress.

After a few days, you should start to see data in your experiments list.

4. Choosing the winner of your experiment

Over time, you should see either the original ad setting or the variation outperform the other. To help you decide the right time to choose your winner, we show you the progress of your experiment. Progress lets you know how many days to go your experiment has before we're confident that either your original ad setting or the variation is the best performing of the two settings. We recommend that you wait until your experiment is marked "Ready to complete" before you choose a setting as the winner. Note that because we calculate progress based on the data that we’ve collected up until now, the number of days to go can go up, down, or stay the same over time.

  • If you choose the original as the winner, then your original settings are retained.
  • If you choose the variation as the winner, then we apply the settings of the variation to your account.

In either case, we stop splitting your traffic, and your experiment ends.

  • If you've opted to let Google choose the winner of your experiment, the best performing settings will be automatically applied for you.
  • If your experiment hasn't reached the "Ready to complete" state after 90 days we'll automatically stop it. When this happens, we’ll revert your settings back to the way they were before the experiment started.

Automatic experiments

Automatic experiments are experiments that Google runs on your behalf. By allowing Google to experiment on your traffic, you get better and more customized opportunities to help improve your account performance. Opportunities from automatic experiments come with a "verified by experiment" label which means that you can be confident in applying their recommended changes right away. 

Automatic experiments run on around 10,000 daily impressions per experiment, or on all daily impressions if you have fewer than 10,000. They test about 50% of those impressions on the new settings and the remainder on your original settings for comparison.

To switch on automatic experiments:

  1. Sign in to your AdSense account.
  2. In the left navigation panel, click Optimization.
  3. Click Experiments.
  4. On the "Experiments" page, switch on automatic experiments.

If you have further questions about experiments, see the Experiments FAQ.

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