Most A/B tests are designed in a way that all but ensures the learnings will not translate into an ongoing lift in sales.

Ultimately, to know with confidence that one creative variation will outperform another, tests must be deployed at the user level, and not the impression level. When tests are run at the impression level, results are far more likely to indicate no difference between creatives. That’s because impressions don’t engage with brands, people do

The large number of inconclusive A/B tests resulting from testing impressions rather than users unfortunately discourages many advertisers from continued testing and optimization. User-focused digital marketers are smarter, however, and demand creative A/B testing that is administered at the user level.

Users Split by Line Item

Tests are all-too-often conducted by comparing the performance of two campaigns or line items being run simultaneously. The problem with this approach is that it does not hold the audience constant, which is a fundamental requirement of A/B testing. Different line items, even with identical settings, will inevitably access slightly different inventory over the course of the test. A proper A/B test in digital advertising must be run on a single line item with the ad server assigning users into groups at each impression so that audience used for the test truly is identical across the test groups.

Testing Plan Siloed from Media Plan

It is critical that creative A/B testing is coordinated with your media agency or in- house programmatic team. Programmatic media buying that is not coordinated with creative optimization can undermine creative tests in the following ways:

Buying low CPM inventory that is less viewable limits the impact of any creative
As discussed in the introduction, creative is growing in importance for multiple reasons, one of which is that digital advertisers are increasingly getting the viewability and attention to their ads that they have been missing. Your creative testing will only be as informative as your ads are viewable. Ad placements that compete with 5-10 other placements on the page may be low in CPM, but the attention garnered makes creative less effective, thus making creative testing less effective. If you’re impressions are 40% unviewable, 40% competing with 5-10 other placements, and only 20% both viewable and prominent, the impact of creative will simply be minimal.

Targeting the same users in the A/B test with other programmatic campaigns
Sometimes when an agency sets up a creative A/B test, they generate a separate placement in the ad server for the test and trafEic it to a line item or package with their trading desk. Such tests are less likely to measure the actual differences in performance between creative variations, because users in the test are being served creatives from other programmatic campaigns at the same time. When providing multiple placements or ad tags to a trading desk, ensure that the trading desk isolates users in a test from other programmatic campaigns.

Creative Test Obscured by Media Attribution

Ad servers, other than Adacus, apply attribution models by default to all conversion reporting. In other words, when a user converts after having seen ads from a test as well as ads from other placements or channels, the ad server will likely not attribute that conversion to the test group to which the user was assigned.
This makes A/B testing all but impossible, for two reasons:

  1. Attribution across channels removes most conversions from the results of an A/B test, thus increasing the amount of testing time required to achieve significance from weeks to months.
  2. Multi-channel attribution introduces noise into the A/B test results. Evaluation of an A/B test does not require multi-touch attribution as users are only presented with the A ad or the B ad throughout the duration of the test.

The solution is to report creative test performance separately from media performance across channels. In the creative test report, include all users that converted after seeing an ad in the test regardless of whether or not they were exposed to media from outside of the test as well.

Learn how to avoid more common pitfalls in our eBook

"The Essential Guide to A/B Testing for Digital Advertisers"