After Politico removed a couple of lines from its original post about l'affaire du McChrystal, coding-savvy Slate reporter, Jeremy Singer-Vine, built a digital watchdog that kept tabs on how often the site changes its posts without telling its readers. I wonder how long before this kind of transparency becomes commonplace. Will media sites, in an effort to build and maintain trust, start providing this data to readers themselves?

How often does Politico, in the din of the news cycle, make significant changes to its copy after publishing it--without telling readers?

Part of the answer, of course, depends on your definition of the word "significant." But part of it is simply math. To get the raw numbers, I wrote a series of fairly simple computer programs to monitor changes to all major Politico articles at regular intervals. (Here is more detail than you probably care to know about the programs.) After three weeks and nearly 400 articles, I have my answer: about 3 percent of the time.

Read the full story at Slate.

Update: Make sure to check out the corrections appended to the story; they appear to take some heat off Slate's fastball.