Almost any question can be answered, cheaply, quickly, and, finally, by a test campaign. And that’s the way to answer them—not by arguments around a table. Go to the court of last resort—the buyers of your product.
—CLAUDE HOPKINSScientific Advertising, 1923
The Holy Grail of direct marketing is the single-variable test. You want only one thing to change in each test. If you’re going to test price, then you test two packages that are the same in all respects except for price.… The goal is to make sure that when something wins or loses on a package or panel, you know the cause of the difference so you can repeat it if it wins.
—DON NICHOLAS in 2,239 Tested Secrets for Direct Marketing Success (Hatch ...