Marketing has always involved wrangling lots of data. Before digital marketing, businesses had to track sales, customer purchases, coupon redemptions, store traffic, and survey responses to understand what their customers wanted.

And while digital marketing didn't invent marketing analytics, it dramatically increased the amount of information out there.

Today, almost every interaction can produce data. A person might see an advertisement, click it, visit a website, read an article, subscribe to an email list, open several emails, add a product to a shopping cart, leave the website, return through a search engine, and eventually make a purchase. And every one of those interactions can potentially become a data point.

For a marketer, this creates an incredible opportunity. It also creates a problem: having more data doesn't automatically result in better decisions.

A company can have hundreds of thousands of customer records and still not know which customers are most valuable.…