Your Secret Weapon: A Horizontal Mailing Test

It’s one of the toughest questions faced by mailers: How often should you mail? The trouble is that customers and prospects can’t all be treated the same.

But you can find the right frequency by doing a horizontal mailing test. Here’s how.

• The test should be set up only with the group of buyers/prospects who would have their mail treatments changed based on results. For example, if you are considering adding a mailing for best buyers only, you should set the test up using only best buyers.
• The test groups must be large enough to get a valid read of the results.
• The test groups must be kept constant throughout the test period. It is vital that those within the test groups don’t migrate to other segmentation groups throughout the test period.
• If you are testing the timing of mailings (such as Groups B and C above) you cannot mail different offers to those two groups. Group B above received Spring 1 and Spring 2 while Group C received Spring 1 and Spring 3. In this case, Spring 1 is the constant, and if there were significantly different results between these two groups, you cannot assume it is due entirely to timing unless Spring 2 and Spring 3 are the exact same offer.
• You must have an idea of what success will look like. In this test, the incremental $/book was $2.11 for the group receiving all three catalogs. If your break-even threshold is higher than the incremental $/book, the roll-out strategy would be to mail only Spring 1 to this group of buyers.
• Keep an eye on other variables which may affect your test. Horizontal mailing tests go on for a long period of time during which other variables such as inventory challenges, major current events, email campaigns, competitor offers, etc. can impact results.

Horizontal mailing tests are a fantastic way to help determine how to treat the different groups of customers and what the impact from your various marketing efforts truly is. As you can see, there is a lot to consider when setting up fair tests and then reading the results.

Tom Blake is senior circulation and marketing manager at San Rafael, CA-based Lenser.