American Cornerstone Institute

How calling out a most popular gift option on a gift array affects donor conversion

Experiment ID: #162516

American Cornerstone Institute

Experiment Summary

Ended On: 10/23/2023

The American Cornerstone Institute is offering a book called “Why America Matters” for a gift of $25 or more through paid Facebook ads. We wanted to test adding a most popular callout to the $50 option on the gift array to see if donors would give a larger amount to receive the book.

Research Question

We believe that the inclusion of a “most popular” callout on a gift array for the $50 option for potential donors will achieve a higher average gift because it leverages the psychological principle of social proof, creating a sense of trust and legitimacy among potential donors.


C: Control
T1: Treatment #1


 Treatment NameConv. RateRelative DifferenceConfidence
C: Control 3.1%
T1: Treatment #1 3.9%27.5% 96.3%

This experiment has a required sample size of 3,645 in order to be valid. Since the experiment had a total sample size of 8,233, 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
× 27.5% increase in conversion rate
× 0% increase in average gift

Key Learnings

The key learning from this experiment is that including a “most popular” callout on a gift array for a specific option can significantly increase donations and average gift. The treatment version, which included a “most popular” callout on the $50 option, resulted in a 27.5% increase in donations compared to the control version. Additionally, the treatment saw a $0.35 increase in gift size with a 95.46% level of confidence.

This experiment demonstrates the power of social proof, where potential donors are influenced by the choices made by others. By highlighting a specific option as the “most popular,” potential donors are more likely to trust and perceive it as a legitimate choice, leading to a higher average gift.

In future experimentation, we should continue to explore the use of social proof in different ways. For example, we can test different callouts such as “best value” or “preferred choice” to see if they have a similar impact on donor behavior. Additionally, it would be beneficial to explore the effect of social proof in other aspects of the donation process, such as the donation page layout or testimonials from previous donors.

Experiment Documented by NextAfter

Question about experiment #162516

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