How an additional call-to-action in a Facebook ad headline affects conversion rate Experiment ID: #8849


Experiment Summary

Timeframe: 4/9/2018 - 4/16/2018

Prior to this experiment, we had validated two related Facebook ad experiments. In one experiment, we learned that a headline focused on the content of the webinar is more effective than a direct call-to-action to reserve your spot. In another, we learned that a more tactics focused headline is more effective than a headline focused on broader fundraising growth.

For this experiment, we wondered if a combination of the two approaches could lead to greater webinar registrations. So for the control, we used the tactics focused headline. For the treatment, we added “Reserve Your Spot »” call to action at the end of the headline.

Research Question

Will adding an additional call-to-action in the Facebook ad headline increase webinar registrations?


C: Tactics
T1: Tactics + CTA


Treatment Name Conv. Rate Relative Difference Confidence
C: Tactics 0.51%
T1: Tactics + CTA 1.4% 164.9% 96.2%

This experiment has a required sample size of 1,107 in order to be valid. Since the experiment had a total sample size of 2,097, 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
× 164.9% increase in conversion rate
× 0% increase in average gift

Key Learnings

This additional call-to-action, paired with the tactics focused headline, increased webinar registrations by 164.9%. This additional clarity showed that there was an action to be taken, rather than simply reading a blog post or article.

Interestingly, there was no significant change in click-through-rate from the ad to the landing page. The control had a 2.3% click-through rate, and the treatment had a 2.5% click-through rate. This implies that by simply priming the user for what they could expect on the next page, we were able to drive more valuable traffic.

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Experiment Documented by...

Nathan Hill

Nathan is an Optimization Evangelist 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.