Count Customers, Not Replies

What it is

It’s a short book, 21 chapters, by the copywriter Claude Hopkins, published in 1923 by his agency, Lord & Thomas of Chicago. He makes his claim in the very first line:

“The time has come when advertising has in some hands reached the status of a science.” Chapter 1

The science he had in mind 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 you’ll take from it

The first thing you’ll take is the habit of testing:

“Almost any questions can be answered, cheaply, quickly and finally, by a test campaign.” Chapter 15

The second is the part that gets left out when people quote Hopkins. 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 might cost $1.50 each, with revenue per customer that “might not in ten years repay the cost of getting.”

Where it shows up in your numbers

Hopkins built the tools you still use every day: the keyed ad, the cost per reply, the test. A century later those 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.

So use his rule the way he wrote it. Test everything, and judge every test on what it costs you to get a customer worth having.