The latest pet rock type craze sweeping corporate America is one worth noting — and adapting.

It’s called the net-promoter score, and it was cooked up by the eggheads at Bain to measure customer loyalty. It’s just as easily applied to donors or other members of your community. It’s based on one devilishly simple question:

“On a scale of 1 to 10, how likely would you be to recommend us to a friend or colleague?”

Now here’s the math: take the percentage who give you a 9 or 10, and subtract from that the percentage who gave you a 6 or less. That’s your net-promoter score. Your 7 and 8 people are deemed to be “passively satisfied” and don’t count one way or another.

A “good” net-promoter score according to the Harvard Business Review Article that launched it would be in the 70s or 80s. I have seen instances, however, where non-profits have ended up with scores below zero.

With baby boomers assuming the donor mantle, it is dangerous to take their loyalty for granted. Here’s an easy to benchmark and easy to track number that will tell you how you’re doing.

Read more in Business Week (registration req’d)

Thanks to the gang at Edge Research for putting me on to this!