Here is an excerpt from an article written by Joan Magretta for the Harvard Business Review blog. To read the complete article, check out the wealth of free resources, and sign up for a subscription to HBR email alerts, please click here.

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I’ve just finished reading Jim Collins’ latest book, Great By Choice (which he co-authored with Morten Hansen). Collins is a smart observer and a gifted writer. It’s hard to put down a Collins book feeling anything but…well, inspired. He’s the coach or the Dad you always wanted. You can do it, he says. You really can. You can choose to be great.

Collins has a knack for asking good questions. In a series of books starting with Built to Last, Collins has addressed every manager’s ultimate anxiety: performance. Each new book finds just the right question, the point of intersection between the timeless issue — performance — and the timely challenge managers are grappling with today. Great By Choice, for example, focuses on why some companies thrive in uncertainty, even chaos, when others do not. Collins works through the question like a detective trying to solve a mystery.

Maybe that’s why reading Great By Choice reminded me of a Sherlock Holmes story — the one about the dog who didn’t bark while the racehorse was stolen from its barn. How did Holmes identify the perpetrator? It was, he told the baffled Scotland Yard inspector, “the curious incident of the dog in the night-time.” But, the inspector replied, “The dog did nothing in the night-time.” Precisely Holmes’s point: “That was the curious incident.” The dog, he reasoned, must have known the thief.

There is one incredibly quiet dog in Collins’ work: strategy. Collins is a master at putting the human face on performance. That, in my opinion, is a significant contribution. Get the right people on the bus. Be disciplined. Be empirical. Be creative. And so on. But good strategy makes the link between the specific actions managers take and the financial results of those actions. Assuming you can figure out who belongs on your bus, someone still must pick a destination. Is it really enough to choose to be great? Don’t you also have to make great choices?

Or let me tone down the rhetoric a notch. You have to make good choices. And that’s where Michael Porter enters the picture. Strategy is not some arcane, academic abstraction. Strategy is about making choices that lead to sustainably superior performance. And the kind of performance I’m talking about can, and must, be rigorously defined and quantified. Porter’s work provides that rigor, as it defines the economic fundamentals of competition and strategy. And most important for managers, Porter’s five tests of good strategy can help you to tell the difference between good choices and bad.

So what are good choices?

[Magretta suggests five “tests” by which to determine whether or not a choice is good or bad. To read the complete article, please click here.]

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Joan Magretta is a senior associate at the Institute for Strategy and Competitiveness at Harvard Business School. She is the author of Understanding Michael Porter: The Essential Guide to Competition and Strategy.