How assumption of desire for an offer affects open rate Experiment ID: #12555

Hillsdale College

Founded in 1844, Hillsdale College is an independent liberal arts college with a student body of about 1,400. Hillsdale’s educational mission rests upon two principles: academic excellence and institutional independence. The College does not accept federal or state taxpayer subsidies for any of its operations.

Experiment Summary

Ended On: 3/11/2019

Hillsdale College was sending complimentary pocket Constitutions to their constituents and donors. They knew they had a list of people who had not received a free pocket Constitution, but they weren’t sure if the people wanted a pocket Constitution. They decided to test two different approaches in the subject line. The first approach asked a question—”Do you want a free pocket Constitution?” The second assumed that they did want it, and offered them to them: “Get your complimentary pocket Constitution”. They split the file and sent a test to determine a winner.

Research Question

How will assuming the recipient wants an offer affect open rate?


C: Question format
T1: Offer format


Treatment Name Open Rate Relative Difference Confidence
C: Question format 6.6%
T1: Offer format 8.7% 30.6% 100.0%

This experiment has a required sample size of 1,316 in order to be valid. Since the experiment had a total sample size of 182,532, 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:

    30.6% increase in traffic
× 0% increase in conversion rate
× 0% increase in average gift

Key Learnings

The subject line that assumed the recipient wanted the offer produced a 30% lift in open rate. There are two possible reasons for this. First, the question format allowed the recipient to decide whether or not to open the email before they even opened the email. If they didn’t want it, many people may have just archived or deleted the email. Second, the two subject lines also used two different words to describe the offer: “free” and “complimentary”. This may have had an impact, as “free” implies that the offer is widely available and of limited value, while “complimentary” implies that the offer is of some value but is given free of charge due to a relationship. This element should be specifically targeted to determine impact in a future test.

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Experiment Documented by...

Jeff Giddens

Jeff is the 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.