Improve E-Mail Response: Test Numerous Variables
How to test e-mail variables, step by step.
How to test e-mail variables, step by step.
In my postal-mail days, there were major variables (offer, price, creative, list, etc.) and minor ones (font, color, graphics, etc.). All affected response rates. The rule of thumb was to first test all the major variables, as they accounted for the greatest response increases. Then, test minor variables to squeeze out even more orders.
In the email world, the postal-mail model must be updated, especially in light of recent stats. First, from an EmailLabs study:
Though the following Advertising.com stats are based on the Web, not specifically email, they offer clues about what variables to consider testing:
Let’s create a comprehensive list of variables to test:
There may be other logical variables to test that are specific to your product or service.
The Right Way to Test
Testing numerous variables in postal-mail days was difficult because we had to create numerous variations of the mail piece and have enough names to test each one. With email, things are a lot simpler.
The key to producing statistically significant test results is to isolate and test each variable independently. To do this, track your testing program on a spreadsheet. Say you want to test 10 variables. You want to use the same list for all tests, so your first test would look like this:
Test variable | Format | Text vs. HTML |
Locked variables | Price | $19.95 |
Offer | Free shipping | |
CTA | Offer expires in 30 days | |
Color | Red | |
Subject line | Creative A | |
Disclaimers | At bottom of email | |
Number of links | 10 | |
Copy length | Short | |
Dominant consumer appeal | Beauty |
You would create two messages, one in text and one in HTML, holding all other variables constant. Once you determine which works best, you move on to the next variable, so the next test would look like this:
Test variable | Price | $19.95 vs. $14.95 |
Locked variables | Format | HTML |
Offer | Free shipping | |
CTA | Offer expires in 30 days | |
Color | Red | |
Subject line | Creative A | |
Disclaimers | At bottom of email | |
Number of links | 10 | |
Copy length | Short | |
Dominant consumer appeal | Beauty |
And so on. Because you can create an email message, send it, and read results within a day or so, you can easily test 10 variables in a couple weeks. Be sure to keep track of how each variable increases or decreases response. Because email is so much easier to test and you can read results faster than postal mail, now’s the time to set up a formal testing program.
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Want more email marketing information? ClickZ E-Mail Reference is an archive of all our email columns, organized by topic.