We learn more from our failures than from our successes. We rarely analyze our successes. If we did, we would quickly find out that luck, timing and a whole bunch of things completely unrelated to our talents were critical components in the making of the deal.

Failure tends to go the other route — we mull the loss of a sale, a client or a big deal over and over again. But we tend to look at every possible cause except our company and ourselves. We sort through all sorts of reasons: the economy is bad, the client is going through a rocky period, their new purchasing manager is crazy, etc.

It pays to examine both failures and successes, to really analyze “the whys” of some recent successes and failures. Ask yourself: Have you lost a client lately? Are sales flat with a client? Are sales going down with a client?

And here’s the killer question: Do you have some kind of “alert” system in place, such that you know when sales for any given client are going down or that activity has gone to zero for another client?

It is impossible to learn from failures if you don’t know about them. Track sales volumes by important customers every week. Sales that are trending down must be addressed. So you notice a decline with a big client. Now what?

Now, with your tracking system in place, you notice a decline in sales activity with a big client. And you would like to know why. Customers are notoriously fickle. They’ll go through the aggravation of switching suppliers when they think they can save some serious bucks.

The best way to find out why your customer dumped you is to ask them. This is very hard to do. Feelings on both sides can make for a very awkward conversation — one that isn’t terribly illuminating about the customer’s defection.

You need someone who is independent of your company to conduct the interviews. Someone with no history will learn far more about the defection. The interview will be informational, not personal. Here’s how you do it.

First: What do you want to learn from the interview? Write the interview script.

Did we deliver on time?

Was the billing correct?

Did we have what you wanted?

Were our prices competitive?

Was there a personality clash?

Second: What about the competition? Unless your former customer is going out of business, they are buying from somebody.

Who are they buying from?

How does the customer experience compare?

Are the prices, services, terms better?

What finally prompted the switch?

Third: Okay — you have your independent person and your script. Have your head of sales ask the customer if an independent consultant can call in the next week and interview the purchaser. Explain that the interview will last about 20 minutes and its purpose is to learn about the company’s experience with your supply house. Make sure you point out and underscore this is NOT a sales call and the person calling is NOT your employee. This is an informational interview.

Fourth: Customers often complain, “They never took the time to understand my problem.” The interviewer must allow the customer airtime to recount his experience with your company. Buyers don’t drop a supply house on a whim. It takes a long string of slights, errors and non-responsiveness that finally culminates in moving to another supplier. Let the guy tell his tale of woe. You will learn far more about the customer’s experience than from specific questions.

When you understand why you have lost customers in the past, you can go a long way towards losing fewer going forward.