Hoover Institution

How long-form copy on Facebook ads affects conversion vs short-form copy

Experiment ID: #11779

Hoover Institution

Experiment Summary

Timeframe: 12/15/2017 - 03/22/2018

We had traditionally used relatively short copy for this client’s ebook offer Facebook ads, usually just one short paragraph briefly describing the offer. However, it was suggested that since we know from previous tests that long-form copy has in some cases outperformed shorter copy on landing pages … why not apply that learning to Facebook ad copy and see if long-form copy in the ad would perhaps convey a greater sense of value and drive more conversions?

Research Question

Would long-form copy in Facebook ads increase the value proposition and drive up conversion rate over ads with short copy?


C: Short-Form Copy
T1: Long-Form Copy


 Treatment NameConv. RateRelative DifferenceConfidence
C: Short-Form Copy 0.35%
T1: Long-Form Copy 0.50%42.2% 100.0%

This experiment has a required sample size of 16,512 in order to be valid. Since the experiment had a total sample size of 891,721, 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:

    0% increase in traffic
× 42.2% increase in conversion rate
× 0% increase in average gift

Key Learnings

The 42% lift illustrates that despite what many might think and what “best practices” might indicate, plenty of people are willing to read through a lengthy post on Facebook if it communicates a good value proposition and speaks to an area of interest to them. And while the audiences for this client may be a bit more philosophical and cerebral than most, the dramatic lift in conversion certainly makes long-form copy in Facebook ads a tactic worth testing with other organizations and audiences as well.

Experiment Documented by NextAfter

Question about experiment #11779

If you have any questions about this experiment or would like additional details not discussed above, please feel free to contact them directly.