How we chose 2015's most disruptive innovators

It takes a trend-spotter to reimagine the world and come up with a bright idea to change things. These futurists all have passions that drive their curiosity. For a look at how they turned their inspirations into reality, one merely has to look at the 2015 CNBC Disruptor 50, our third annual roundup of the country's most ambitious and innovative private companies revolutionizing their industries—and the economic ecosystem.

The common denominator? All of these companies entered traditional sectors and turned them upside down. About half of this year's disruptors are last year's alumni that have inspired incumbent companies to adopt their new business models.

Read MoreFULL LIST: 2015 DISRUPTOR 50

For this year's list, CNBC updated our selection process. Instead of relying solely on submissions from venture capital firms through the National Venture Capital Association, as we did in years past, we opened nominations to the public at large. Nominees were required to submit a detailed analysis of companies for consideration that included key quantitative and qualitative information. This led us to expand the universe of potential contenders beyond those favored by their VC backers. As a result, we received nominations directly from entrepreneurs in the U.S. and abroad.

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The new nomination process brought in close to 400 candidates. Companies were then put under a months-long process of research and scoring, using a proprietary blend of quantitative criteria, such as the amount of venture capital raised, off-the-record information on sales and user growth, along with qualitative criteria, including originality, scalability and creating a new market or ecosystem.

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The process also included a survey by CNBC's Disruptors Advisory Council (see list below)—a group of 10 leading academics in innovation and entrepreneurship—to rank the criteria in terms of impact on the company's overall ability to disrupt established industries and public companies. The council found that "creating a new market or ecosystem" and originality were the two most important criteria in determining how disruptive a start-up is to established companies or industries.

However, this selection process still has its limits. First, we recognize the nomination process may underrepresent companies or even industries that did not choose to enter our selection process. We used the start-up data site CrunchBase.com to acquire a consistent set of quantitative data for some criteria. Recognizing that some criteria are subjective, we designed our model to ensure that no single criterion can carry enough weight to render the final ranking unfair.

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That said, the 2015 CNBC Disruptor 50 collectively have the potential to impact multibillion- and multitrillion-dollar industries. They have raised more than $22 billion in venture capital to date and employ thousands of people. And they represent breakthrough ideas coming out of Silicon Valley, New York City and a few points elsewhere. Would you believe Stockholm, Sweden?