Editor's note: Terry Vavra and Doug Pruden are partners at Customer Experience Partners LLC. They can be reached at terry@terryvavra.com and pruden@customerexperiencepartners.com, respectively.

In a profession that is driven by information about current and potential customers, a source of remarkable insight is frequently overlooked. We’re referring to defecting and lost customers. Let’s face it: As managers we don’t like to relive or review our mistakes and that’s what lost customers are, right? We’ve done something or failed to do something else which results in a customer walking away. Rather than reliving the frustration by investigating the departure, we’re happier bumbling forward and unknowingly making the same mistake(s) over and over again!

Also preventing fully tapping into this source of insight are the actions of defecting customers. They can be divided according to how vocal they are. Many will simply leave in silence – the passive defectors, whose information is not volunteered to the marketer. Others, recognizing their investment in time with a supplier, will reach out to express the issue or problem precipitating their departure – the active defectors. Both have valuable information for the marketer. But the insights from passive defectors will never be heard without an outreach to them. And, because actives are the vocal minority, effort must be taken to see that their feedback is properly weighted versus any information collected from passives. 

While marketers are routinely comfortable spending resources on studying current customers, interviewing lost or departing customers may be considered a waste of time. But collecting feedback from defecting customers is a sound business practice. The philosophy behind such actions is analogous to the “zero defect” philosophy of manufacturing. A manufacturer doesn't look to its acceptable products as a way to improve a manufacturing process;...