When is an opportunity worth pursuing?

One of the biggest challenges in business is to tell the difference between a great idea and a true opportunity. They are not the same.

Ideas can be enticing, provocative, engaging. "Let's build a better portal for research scientists," is an idea.

But an opportunity is different. It needs to be rooted in a substantive and lasting change in the world.

"Since wireless service now pervades major cities and includes automobiles, let's create a better way to manage the limited supply of parking spaces," might describe a major opportunity. The founders of Streetline think so, and you could argue that they are bringing intelligence and useful data to an industry that until now has lacked both.

Substantive and lasting changes have many potential sources, such as new technology, new regulations or even climate change. A great deal of money is likely to be spent over the coming decade protecting property against the perceived increasing frequency of extreme storms.

There's nothing wrong with an idea. They are the starting point of creativity. But don't stop there. Test your ideas, to see if any represent true opportunities:

Why now? What has changed in the world to create a substantive opportunity? If you can't name anything, then there's probably not an opportunity there.

Will it last? Sometimes you have to make a bet whether a change is long-term or fleeting. NASA's lack of funding looks to be long-term, and represents an opportunity for risk-loving space entrepreneurs. But a year ago it was difficult to predict whether Obamacare would be overturned or not.

Is it big enough? When iPhones first appeared, they brought with them the App Store and created significant opportunities for developers to become entrepreneurs. But when Apple replaces, say, the iPhone 3 with the 4, the changes often are not significant enough to create opportunities for entrepreneurs.

Explore ideas, but bet on opportunities.