John J. Kilcullen
Chairman and CEO of IDG Books Worldwide, creator of the Dummies series of how-to books.

The biggest mistake I made was not collecting relevant data about our customers in the early days. Success in publishing evergreen best-sellers requires a careful balance of intuitive judgment and customer research. Although we grew very fast and turned a profit in less than two years, I wish our reader database had grown just as fast.

To better understand our customers in the early years, we conducted reader research using "bounce back" cards placed in our books.

But we didn't create an inventory of those names in a database or perform any "data mining" for psychographic information (such as readers' responses to the question "How do you feel about buying a book that describes you as a 'dummy'?"). In branding, it's critical to understand your customers' emotional attachment to your product or company.

So we missed the mark a few times. Seven of our first nine publications failed. During the early 1990s we published three books on Microsoft DOS. The first failed outright, and the second was only moderately successful. Then we launched DOS for Dummies, which became an international best-seller. We might have had success with the first book -- and saved hundreds of thousands of dollars in unnecessary costs -- if we'd done prepublication research to sharpen our focus. If we had used our data more wisely during those years, we might have developed new products more efficiently and achieved more cost-effective and targeted direct marketing.

Two years ago we started using the Internet to connect with our customers. With sites like, we're learning more about our readers and why they feel excited about our product line. And that gives us the confidence to expand the brand into new subject categories, like Golf for Dummies and Wine for Dummies. --Written with Anne Marie Borrego