The Heritage Foundation

How a more personal subject line affects open rate

Experiment ID: #1366

The Heritage Foundation

Founded in 1973, The Heritage Foundation is a research and educational institution—a think tank—whose mission is to formulate and promote conservative public policies based on the principles of free enterprise, limited government, individual freedom, traditional American values, and a strong national defense.

Experiment Summary

Timeframe: 12/10/2014 - 12/18/2014

With a little more than two days left before the end of the year, Heritage Foundation email subscribers had received six different messages from Jim DeMint– the president of the organization– asking for their support with a year-end gift. Best practices suggest that the email signer should be the most publicly know leader of the organization, and should rarely (if ever) change to ensure donors hear a consistent voice. Heritage tested that theory by sending an email from someone else in the organization.

Research Question

How does a more personal subject line impact open rate?


C: Control
T1: Personal Subject Line


 Treatment NameOpen RateRelative DifferenceConfidence
C: Control 16.9%
T1: Personal Subject Line 33.6%98.8% 100.0%

This experiment has a required sample size of 52 in order to be valid. Since the experiment had a total sample size of 169,912, 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:

    98.8% increase in traffic
× 0% increase in conversion rate
× 0% increase in average gift

Key Learnings

This test proved that a more personalized message, even if not from the primary organizational sender, can have a significant impact on open rate — and therefore the donor’s likelihood to give.

Experiment Documented by Dan VanMilligan
Dan VanMilligan is Implementation and Optimization Specialist at NextAfter.

Question about experiment #1366

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