Thursday, June 18, 2009

Root Cause Analysis

An Interesting Customer Complaint

This is a real story that happened between the customer of General
Motors and its customer-care executive. A complaint was received by
the Pontiac Division of General Motors: This is the second time I
have written to you, and I don't blame you for not answering me,
because I sounded crazy, but it is a fact that we have a tradition in
our family of ice cream for dessert after dinner each night. But the
kind of ice cream varies, so every night, after we've eaten the whole
family votes on which kind of ice cream we should have and I drive
down to the store to get it.

It's also a fact that I recently purchased a new Pontiac and since
then my trips to the store have created a problem. You see, every time
I buy a vanilla ice cream, when I start back from the store my car
won't start.

If I get any other kind of ice cream, the car starts just fine.

I want you to know I'm serious about this question, no matter how
silly it sounds: "What is there about a Pontiac that makes it not
start when I get vanilla ice cream, and easy to start whenever I get
any other kind?"

The Pontiac President was understandably skeptical about the letter,
but sent an engineer to check it out anyway. The latter was surprised
to be greeted by a successful, obviously well educated man in a fine
neighborhood. He had arranged to meet the man just after dinnertime,
so the two hopped into the car and drove to the ice cream store. It
was vanilla ice cream that night and, sure enough, after they came
back to the car, it wouldn't start.

The engineer returned for three more nights. The first night, they got
chocolate. The car started. The second night, he got strawberry. The
car started. The third night he ordered vanilla. The car failed to

Now the engineer, being a logical man, refused to believe that this
man's car was allergic to vanilla ice cream. He arranged, therefore,
to continue his visits for as long as it took to solve the problem.
And towards this end he began to take notes, he jotted down all sorts
of data: time of day, type of gas used, time to drive back and forth
etc. In a short time, he had a clue: the man took less time to buy
vanilla than any other flavor. Why? The answer was in the layout of
the store. Vanilla, being the most popular flavor, was in a separate
case at the front of the store for quick pickup. All the other
flavors were kept in the back of the store at a different counter
where it took considerably longer to check out the flavor. Now, the
question for the engineer was, why the car wouldn't start when it took
less time. Once time became the problem and not the vanilla
ice-cream, the engineer quickly came up with the answer: "Vapor
lock". It was happening every night; but the extra time taken to get
the other flavors allowed the engine to cool down sufficiently to
start. When the man got vanilla, the engine was still to hot for the
vapor lock to dissipate.

Remember: Even crazy-looking problems are sometimes real and all
problems seem to be simple only when we find the solution with a cool