Dallas Theological Seminary

How images in an email affect clickthrough rate

Experiment ID: #3884

Dallas Theological Seminary

The DTS mission is, “to glorify God by equipping godly servant-leaders for the proclamation of His Word and the building up of the body of Christ worldwide.” They strive to help men and women fulfill the Great Commission and the Great Commandment, or more simply: Teach Truth. Love Well.

Experiment Summary

Timeframe: 04/22/2016 - 05/04/2016

Dallas Theological Seminary was promoting their newest online course on Genesis to their house file. Many of the people in their house file had already taken one of their first two courses.

Previous testing had shown that their prospects responded well to very personal invitations. However, they wanted to try a more graphical approach that presented the new course in a more dramatic way and gave the reader more to click on.

They created a treatment that inserted an image from the course into the copy (linked to the registration page) and put an image of Dr. Mark Bailey, the sender, next to his signature.

They split the file and sent an A/B email test to determine a winner.

Research Question

Will additional imagery increase clickthrough rate?


C: Personal text-based email
T1: Email with imagery


 Treatment NameClick RateRelative DifferenceConfidence
C: Personal text-based email 7.4%
T1: Email with imagery 16.9%129.9% 100.0%

This experiment has a required sample size of 82 in order to be valid. Since the experiment had a total sample size of 45,265, 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:

    129.9% increase in traffic
× 0% increase in conversion rate
× 0% increase in average gift

Key Learnings

This tells us that when we are introducing a new course to our donors, we must be somewhat visual about it. Though previous testing had shown the power of a personal invitation, imagery can help attract attention and win more clicks and registrations.

Experiment Documented by Jeff Giddens
Jeff Giddens is President of NextAfter.

Question about experiment #3884

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