How To Split-Test Google Ads Using “Split Tester”
Beware: When you test, you need reliable numbers!
This means you need enough trials to be sure your results weren’t just luck. If you flip a coin four times and it comes up heads all four, it doesn’t mean there’s no tails. On your next flip there’s still the same 50% probability of getting either heads or tails.
A rule of thumb for testing is: You need at least 30 responses, under a consistent set of conditions, for your numbers to be accurate within 5%.
So if you’re split testing two pay-per-click ads on Google, one gets 5 clicks and the other 10, you really don’t know which one is better yet. It could just be luck. But when one gets 30 and the other 50, you’re pretty certain.
The same is true with direct mail, responses to a web page, e-mail, or whatever. At least 30 responses for each item you test.
COOL TIP: 30 is STILL just a rule of thumb. But I created this cool tool that tells you just how certain you are. You plug in the CTR’s and the number of clicks for two ads and this tool tells you:
Example:
Ad #1 – 25 clicks, 3.1% CTR Ad #2 – 17 clicks, 1.5% CTR
Click “submit” and the tool replies:
“You are approximately 95% confident that the ads will have different long term response rates.”
Testing used to be a lot harder than it is now. Read Scientific Advertising, written in 1918 by Claude Hopkins. He talks about taking months to run ads in newspapers, collect coupons from retail stores, and assess campaigns’ success.
Now you can send out a few thousand e-mails, split between multiple offers, and you know within a few hours which is better.
Testing used to be very expensive and take weeks or months. Now it’s cheap and it takes hours or days. There’s no reason why you can’t know anything you want to know with inexpensive testing! And no reason to spend millions of dollars developing an idea that nobody will buy. Sales people look at rejection as failure, but direct marketers see it as only a test. Which way do you want it?
Testing weeds out those bad ideas, and leads you to the good ones. The answers will always surprise you.
To Your Success,
Perry Marshall
