Research library Required reading Where it started
Count the Customers, Not the Replies.
In 1923 Claude Hopkins argued that advertising had become a science, because a keyed ad could be traced, counted and tested. In the same chapter he warned that some replies are worthless. That warning is the half most teams skip.
Claude C. Hopkins · Scientific Advertising · 1923
What it is
A short book, 21 chapters, by the copywriter Claude Hopkins, published in 1923 by his agency, Lord & Thomas of Chicago. Its claim is in the first line:
“The time has come when advertising has in some hands reached the status of a science.” Chapter 1
The science was mail order. Every reply came back on a coupon or with a key, so every ad could be traced to what it produced and compared with every other ad. Hopkins took that discipline and applied it to advertising in general.
What we took from it
The habit of testing, first:
“Almost any questions can be answered, cheaply, quickly and finally, by a test campaign.” Chapter 15
And the part that usually gets left out when Hopkins is quoted. Replies were never his finish line:
“One ad may bring too many worthless replies, another replies that are valuable. So our final conclusions are always based on cost per customer or cost per dollar of sale.” Chapter 1
In a chapter called “Things Too Costly,” he even does the lifetime math: customers that might cost $1.50 each, and revenue per customer that “might not in ten years repay the cost of getting.”
Where it shows up in our work
Hopkins built the tools every performance marketer still uses: the keyed ad, the cost per reply, the test. A century later the tools run automatically, and the warning that came with them is gone. The ad that brings in the cheapest replies wins, whether or not the replies were worth anything. That’s the Free Lamborghini.
Our version of his rule: test everything, and judge the test on the cost of a customer worth having.
Next on the shelf Eugene M. Schwartz, Breakthrough Advertising