Here’s a lesson from Asymco‘s Horace Dediu in how to add color and value to raw data.

First he did what comScore should have done when it released its February U.S. mobile phone market report: He graphed the data, showing not only comScore’s latest numbers, but the trend lines dating back two years. (See chart at right.)

Then he correlated the February data with something Canaccord Genuity’s Mike Walkley wrote a couple days earlier:

“We believe iPhones are outselling all other smartphones combined at Sprint and AT&T and selling at roughly equal volume to all Android smartphones at Verizon.”

Putting the two reports together, Dediu concluded that roughly half of the iPhones Apple (AAPL) sold between November 2011 and February 2012 were bought as replacements for existing iPhones.

(You have to read his post to follow the logic. He assumes, for one thing, that the number of Google (GOOG) Android phones bought as replacements is minimal since the most of them are less than two years old.)

Finally, he boils his findings down into an easy-to-remember aphorism:

Loyalty must be earned and preserved. I.e. “You come for the product, you stay for the ecosystem.”

“So far,” he writes, “the iPhone seems to be getting a passing grade while Android has yet to face the test.”

You can read Dediu’s full report here.