How an open field on a donation form affects donor conversion rate Experiment ID: #6700


CaringBridge offers free personal, protected websites for people to easily share updates and receive support and encouragement from their community during a health journey. Every 7 minutes, a CaringBridge website is created for someone experiencing a health event.

Experiment Summary

Timeframe: 5/14/2017 - 6/6/2017

CaringBridge had executed several tests on their main donation page and found that the motivation to give on that page was very different than on their “tribute” pages, which was where most of their revenue came in. Their main donation page had a high average gift, and the motivation to give had proven to be much less personal and much more mission-based.

Since average gifts were high on this page, they wondered if the six-button gift array (which had beaten a three-button array in a previous test) were actually hindering average gift and conversion. The suggested gift amounts were meant to provide relief to decision friction—but what if they added to it?

CaringBridge decided to test this array against an “open field”, which allowed the donor to decide on their own gift amount, with a stated minimum donation of $10. They split the traffic to determine which had a greater effect on donor conversion rate.

Research Question

How does an open field on a donation form affect donor conversion rate?

MECLABS Conversion Factors Targeted

C = 4m + 3v + 2( i - f) - 2a ©

Copyright 2015, MECLABS


C: Six-Button Array
T1: Open Field


Treatment Name Conv. Rate Relative Difference Confidence
C: Six-Button Array 3.3%
T1: Open Field 7.4% 125.9% 99.0%

This experiment has a required sample size of 226 in order to be valid. Since the experiment had a total sample size of 785, 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
× 125.9% increase in conversion rate
× 0% increase in average gift

Key Learnings

The treatment produced a 125.9% lift in conversion on the main donation page. This showed that the array, which was designed to combat decision friction, might have actually contributed to it. One danger in the open field treatment was that average gift would dip without the suggested amounts to provide “anchors”. CaringBridge kept a close eye on average gift, but found no valid difference in the two forms, which meant that there was a valid revenue increase from this test.

This prompted a series of tests to separate desktop traffic from mobile and determine the individual impact of each experience on conversion.

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Experiment Documented by...

Jeff Giddens

Jeff is a Senior Vice President 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.