Great companies thrive on innovation — finding new solutions to old problems, better ways of handling everyday tasks, or anticipating needs and desires other people aren't even aware of. And they're never satisfied with "good enough" — else we'd still be using VCRs to record shows while tapping away at our Windows 95 desktops.

What's true for businesses also holds for this, The Seattle Times' 21st annual performance ranking of Northwest public companies. Over the years we've tweaked and tucked our formula, of course, but as the ranking enters its third decade it seemed time for a top-to-bottom overhaul.

We started as we always do: with all companies headquartered in Washington, Oregon or Idaho (sorry, Boeing) and traded on a major stock exchange. Then we eliminated companies that went public during 2011 (see you next year, Zillow) or whose stock price fell below $2 at any time during the year (better luck next time, Clearwire). That left us with 96 companies that could be ranked.

Savvy analysts and investors know that no one statistic or ratio can capture all dimensions of a company's performance. We settled on four key measures: free cash-flow yield, return on invested capital (ROIC), asset turnover and stock-price appreciation. Together, those stats get at a business's main purpose: efficiently using resources to earn a return for the owners.

We gathered most of the raw data from Bloomberg News, supplemented by company reports filed with the Securities and Exchange Commission. We ranked all 96 companies separately on each metric, then weighted the four subscores and combined them into an overall score. Though free cash-flow yield gets the most weight, no single measure predominates; companies need to outperform across the board to rise to the top.

To minimize distortions due to companies' differing fiscal years, we used trailing 12-month data (as of early March) for all rankings except stock price, which was based on calendar 2011. Companies whose stocks lagged the Russell 3000 or had negative free cash-flow yield got no points in those categories.

The table here displays the key data.