First-Order Measurement

Sep 24th, 2002 by Tony in QSM2

Mr. and Mrs. Tweedle had 15-year-old twins, Dum and Dee, who were just learning to drive a car. Dee had driven the family car ten times, and she had a perfect safety record. Dum had also driven the car ten times, but he had been involved in three wrecks. Mrs. Tweedle told Mr. Tweedle that he had to have a talk with the boy, before someone was killed.

Mr. Tweedle opened the conversation by reviewing the three accidents, then asked Dum, “What do you have to say for yourself?”

“Well, three accidents out of ten trips isn’t such a bad percentage.”

“I might agree with you,” said Mr. Tweedle, “but your sister, Dee, has also made ten trips without so much as a stone chip on the windshield.”

“That’s true,” said Dum, “but I get much better gas mileage than she does. And I don’t get mud on the tires.”

“Oh,” said Mr. Tweedle. “I hadn’t thought of those things. Well, just try to drive more carefully from now on, and keep up the good work on mileage and cleanliness. I’m going to have to talk to your sister about her driving habits.”


As John von Neumann said, “There’s no sense being precise about something when you don’t even know what you’re talking about.”

A company that wrecks three out of ten major software projects is not ready for second-order measurement. Even worse, if such a company attempts to install a measurement program based primarily on second-order measurement, they will do more harm than good.

If you work in an organization that churns out software products on time, within budget, that please your customers and continue to please them over their useful life-and you do this at least 99% of the time-then you won’t need to read First-Order Measurement.

But if your organization doesn’t meet these criteria, then I hope to show you how to create “a positive environment for measurement,” to avoid the costly mistakes that have led to failure of so many measurement programs, and how to measure things simply and efficiently-things that will help your organization consistently produce the quality software you want.

— Jerry Weinberg, Quality Software Management Vol 2, Preface

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