Luther Seminary

How using a minimalist ebook cover affects content offer signup conversion

Experiment ID: #205176

Luther Seminary

Experiment Summary

Timeframe: 06/01/2026 - 07/08/2026

Luther Seminary is a theological education institution that equips Christian leaders and provides resources to help people deepen their understanding of faith and Scripture. As part of its digital fundraising program, Luther Seminary offers free educational resources that invite people to engage with its content and, after signing up, make an immediate donation.

Study guides focused on individual books of the Bible had historically been effective content offers for Luther Seminary. For this experiment, we wanted to understand whether the visual style of an ebook cover could influence engagement throughout the offer funnel.

The control used Luther Seminary’s traditional ebook cover style, featuring an image of an open Bible with a high-contrast title prominently displaying the name of the study guide. The treatment introduced a more minimalist and modern design, using significant white space and purposeful use of color rather than a photographic image.

The new artwork was introduced consistently across the campaign, beginning with the advertisements promoting the study guide and continuing through the content offer signup experience. While the artwork could affect initial engagement with the ads, the experiment was designed to evaluate whether that increased interest translated into meaningful downstream behavior, specifically content offer sign-ups and immediate donations after registration.

Research Question

We believe that presenting the Bible study guide with a more minimalist, modern cover design would increase content offer sign-ups and instant donations compared with the traditional cover design because the updated visual style would make the resource feel more contemporary and engaging, increasing a prospective reader’s interest in obtaining the resource and continuing through the funnel.

Design

C: Traditional Cover

T1: Minimalist Cover

Results

	Treatment Name	Conv. Rate	Relative Difference	Confidence
C:	Traditional Cover	6.1%
T1:	Minimalist Cover	6.4%	3.9%	5.5%

This experiment has a required sample size of 78,590 in order to be valid. Unfortunately, the required sample size was not met and a level of confidence above 95% was not met so the experiment results are not valid.

Key Learnings

Additional Results Measured

Ad engagement

Control: 103 unique clicks from 6,134 samples, a 1.7% click conversion rate
Treatment: 2,145 unique clicks from 122,411 samples, a 1.8% conversion rate
Relative Difference & Confidence: 4.4% relative increase at 33.6% confidence

Landing Page Sign-Ups

Control: 49 email sign-ups from 103 visitors, a 47.6% conversion rate
Treatment: 1,210 sign-ups from 2,145 visitors, a 56.4% conversion rate
Relative Difference & Confidence: 18.6% relative increase at 92.0% confidence

Key Learnings

The minimalist, modern cover treatment produced a higher observed conversion rate at all three stages of the funnel, but the evidence was not strong enough to declare a statistically valid winner.

The clearest directional difference occurred on the content offer landing page. Visitors exposed to the modern cover were 18.6% more likely to sign up compared to the traditional cover. This result reached 92.0% confidence, which suggests a potentially meaningful effect but falls short of the 95% threshold required to consider the result statistically valid.

The differences at the beginning and end of the funnel were much smaller, and those results had low statistical confidence. We cannot conclude that the cover treatment caused an increase in ad clicks or instant donations.

The large imbalance in sample sizes between control and treatment should also be considered when interpreting the experiment. This imbalance occurred because of the open targeting of the Meta algorithm, allowing Meta's bidding tools to scale ad spend on the most engaging ads.

The results provide some directional evidence that the visual presentation of the resource may matter most when a visitor is deciding whether the content itself is worth acquiring.

The minimalist treatment may have made the study guide feel more contemporary, polished, or valuable, which could help explain the comparatively larger lift on the signup page. This interpretation is consistent with the original hypothesis, but the experiment does not establish why visitors behaved differently.

Importantly, the same effect did not clearly carry through to instant giving. Once someone had already decided to obtain the resource, the cover artwork may have had relatively little influence on the separate decision of whether to donate.

Next Steps for Testing

The strongest next step would be to retest the modern-versus-traditional cover treatment with a more balanced allocation between control and treatment, focusing primarily on landing-page signup conversion. The 18.6% directional lift at 92% confidence is strong enough to justify additional testing, but not strong enough to establish the modern design as the winner.

A follow-up experiment could also isolate which aspect of the modern treatment is responsible for any improvement—for example, testing photography versus illustration, high visual density versus white space, or traditional versus contemporary typography.

Experiment Documented by NextAfter

Question about experiment #205176

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