List Testing in Direct Mail

List Testing in Direct Mail

“If you mail an entire mailing list the first time you try it, you aren’t testing, you’re gambling.”

-Edward Nash [1]

When looking at your marketing budget, testing should always be included as a necessary upfront expense. The reason is that companies can “assume” a launch will be successful and then run the risk of blowing their entire marketing budget on an untested launch that doesn’t produce anticipated results.

Although testing elements of your mail campaign may cause delays in the rollout and often requires additional investment, it is more likely to lead to a successful launch and help you establish control that produces consistent results.

A successful pre-launch test will help identify the combination of elements you’re seeking to test: mailing list, offers, and creative, that can validate a campaign launch. Likewise, it will help you identify elements that may suppress response.

There are many elements to test in your direct mail campaigns, the most important are list, offer, and creative. In this month’s article, we will focus on list testing, followed by offer and creative testing in subsequent months.

List Testing

List testing should be a true sample that represents the larger population of your list. An easy way to do this is to take your entire mailing list and divide it by the number of people you want to test in the group. If the number to test is 500 and your total mailing list is 10,000, you will select every 20th person on the list so that you can get an accurate and precise sampling of the audience you intend to target in your overall campaign. [1]

Think About Segmentation Before Sending a Test

Segmenting your audience is another good idea when you’re testing. If you are a local bank that intends to reach people within a 5-mile radius of your location, you may want to segment further into testing groups such as annual household income, homeowners, or credit-card users, depending on the details of the offer you’re testing.

Understanding the demographics of your best customers, then selecting other consumers who have similar characteristics, will likely deliver much better response than sending to a large list of people that only share one or two things in common [2]. (See our blog about further detail on segmentation.[3])

A Word on Timing 

If you intend to reuse a list from a control campaign that did well in the past, you’ll need to take into consideration the fact that passing time can, and usually does, affect the outcome of a test. Changes like age, economy, social status, and career are just some of the factors that may have changed for the individuals on the list. Be aware that these changes often affect how a test might go if using an old list. Since time is a detail that can’t be controlled, it is a good idea to make sure you’re getting fresh, updated lists for your target market prior to testing them.

Test Extension

Once you’ve narrowed down the sample size of your list, and have a mail piece with a compelling offer and a creative format that is designed for your target audience, you can mail to the test sample. If the outcome of the test is favorable, you can do a “test extension”, which is a re-mailing to a larger sample size from the initial list from which the sample was chosen, before doing a full rollout and mailing to the entire list. This test extension allows for more certainty prior to making the commitment to the full campaign.

Coming Up

Stay tuned for additional blogs in the coming months. In the upcoming blogs, we’ll review the key points of testing an effective offer, developing a creative format, testing all the elements, and putting your test budget to good use.


  1. Nash, Edward. Direct Marketing. New York: McGraw Hill, 2000. Print.


About Genesis Direct

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