How a personalized note affects clickthrough rate on a Facebook ad Experiment ID: #7497

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: 9/6/2017 - 9/25/2017

Hillsdale College’s course, “An Introduction to C.S. Lewis: Writings and Significance” has remained one of their most popular courses over the last few years. After receiving a significant amount of positive feedback, they found that many people wanted to own a DVD version of this course. So they created a DVD Box Set and began to offer it to their fans online. As they began this new campaign, they wondered: Will a personal note from Dr. Larry Arnn increase the motivation and clickthrough rate of the ad viewer? They created a treatment and launched an A/B test to find out.

Research Question

Will a personal note from Dr. Larry Arnn increase clickthrough rate on a Facebook ad?


C: Control
T1: Treatment 1


Treatment Name Click Rate Relative Difference Confidence
C: Control 1.4%
T1: Treatment 1 1.2% -12.5% 99.8%

This experiment has a required sample size of 33,602 in order to be valid. Since the experiment had a total sample size of 176,638, 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:

    12.5% decrease in traffic
× 0% increase in conversion rate
× 0% increase in average gift

Key Learnings

Hillsdale College found that the personal note treatment version decreased clickthrough rate by 12.5%. There are a couple of possibilities for this slight decrease. First, it’s possible that this treatment version actually decreased the clarity of the offer. While it did add more context to why the DVD box set was being offered, it did not explicitly mention the DVD box set. Second, it’s also possible that this message from Dr. Arnn increased the anxiety of the ad viewers. They may have hesitated and wondered if Dr. Arnn really did say those words.

While these results are valid, this test has prompted further studies with different types of offers to further prove if a personalized note increases or decreases clickthrough rate on a Facebook ad.

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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.