How Ad Congruency Affects Clickthrough Rate on a Facebook Ad Experiment ID: #7396

Hillsdale College

Founded in 1844, Hillsdale College is an independent liberal arts college with a student body of about 1,400. Hillsdale’s educational mission rests upon two principles: academic excellence and institutional independence. The College does not accept federal or state taxpayer subsidies for any of its operations.

Experiment Summary

Timeframe: 7/24/2017 - 9/12/2017

Hillsdale College found in a previous test that adding course illustration improved clickthrough rate significantly, while increasing email acquisition rate by 85%. As they began to test this approach with other offers, they noticed that some of their offers have a variety of illustrations to choose from–their “Great Books 102” course offering, for example. Examining this particular course, they wondered: Will a course illustration that directly reinforces the authors mentioned in the ad copy increase clickthrough rate? They launched an A/B test on their ‘Great Books 102’ course to find out.

Research Question

Will a course illustration that directly reinforces the ad copy increase clickthrough rate?


C: Control
T1: Treatment 1


Treatment Name Click Rate Relative Difference Confidence
C: Control 0.25%
T1: Treatment 1 1.3% 406.9% 100.0%

This experiment has a required sample size of 755 in order to be valid. Since the experiment had a total sample size of 41,998, and the level of confidence is above 95% the experiment results are valid.

Flux Metrics Affected

The Flux Metrics analyze the three primary metrics that affect revenue (traffic, conversion rate, and average gift). This experiment produced the following results:

    406.9% increase in traffic
× 0% increase in conversion rate
× 0% increase in average gift

Key Learnings

Hillsdale College found that the treatment version increased clickthrough rate by 406%. It’s apparent that the course illustration that contained images of the authors discussed in the ad copy reduced the viewer’s anxiety (i.e. Who is Jane Austen or Mark Twain? What do they look like?), subsequently increasing the congruency entire Facebook Ad and the clarity of the value proposition. This test shows us that, when using course illustrations in an ad, it’s important to make sure that the ad image supports the body copy in the ad itself.

Hillsdale College has since adopted this treatment version as the champion control across all of their “Great Books 102” audiences, and they have seen a significant increase in total traffic to their course signup page.

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Experiment Documented by...

Kevin Peters

Kevin is the Chief Technology Officer at NextAfter. If you have any questions about this experiment or would like additional details not discussed above, please feel free to contact them directly.