Does shorter copy perform better in email when introducing a pledge? Experiment ID: #9423

Care Net

Experiment Summary

Ended On: 8/3/2018

Care Net found in previous tests that longer copy appeals performed better in email that shorter ones. Our hypothesis was that recipients needed the additional value proposition in order to make a gift. When launching our new pledge, we wanted to see if people needed longer copy to click through an email to sign a pledge or if shorter copy performed better.

Research Question

Since signing a pledge requires much less commitment than making a donation, would using shorter copy in an email result in more people signing the pledge?


C: Control (Longer Copy)
T1: Shorter Copy


Treatment Name Click Rate Relative Difference Confidence
C: Control (Longer Copy) 1.9%
T1: Shorter Copy 3.9% 101.0% 100.0%

This experiment has a required sample size of 571 in order to be valid. Since the experiment had a total sample size of 53,725, 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:

    101.0% increase in traffic
× 0% increase in conversion rate
× 0% increase in average gift

Key Learnings

The shorter copy had significantly more clicks and, as a result, significantly more people who signed the pledge on the landing page. Interestingly enough, once on the landing page, contacts that converted on the shorter email also converted at a higher rate than those who came through the longer email. (82.64% vs 80.94%). This experiment shows that the perceived cost of an action impacts the length of copy necessary to prove the value of that action. We will now test this learning on our Facebook ads to see if they perform in similar ways.

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Experiment Documented by...

Courtney Gaines

Courtney is the Senior Director of Optimization 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.