When you have well over half a million customers, it's almost impossible to understand the likes and dislikes of each or what motivates them to buy your products. But as the manager of Dow Jones Interactive's Wall Street Journal Online knows, if you can understand how customers behave, you can get much closer to delivering what they want.

When you have as many different types of subscribers as WSJ Online does, that's no small feat. Some go directly to the site to sign up; some receive the print version but also want the online version, which they get for a discount. Some are corporate subscribers, and some pick up subscription information at Barnes & Noble. "The incredible thing is, that's not even all of the ways people can subscribe," says Todd Larsen, general manager of consumer electronic publishing for WSJ Online. "Trying to understand how all these groups behave on the site and why is a major challenge."

The trick, he says, is to correlate the log and clickstream information generated by the Web site with the customer files. Though the online staff has been able to grab that information for some time, it wasn't easy. Doing so required manually matching files, which was time-consuming and prone to errors.

That's why in 2001, the online team started evaluating more automated approaches, such as data mining and analytics (or business intelligence). After considering outsourcing the project and building its own data warehouse, WSJ Online signed up with data-mining and analytics provider digiMine in December of last year. The goal was to have a data infrastructure ready for WSJ Online's relaunch on January 28, 2002.

digiMine delivered on time, and the company's services are now helping Larsen and his team better understand how the site is performing and devise improvements. WSJ Online's department heads and marketers now have access to analysis that helps them identify which customer groups are worth spending marketing dollars on. They can also determine the best pricing models. The point, of course, is to boost the bottom line.

"When we started this process, we were looking at the return-on-investment factor," says Larsen. "Making better marketing-spend and pricing decisions definitely justifies the investment here."