Google just announced via Twitter that it started rolling out a Panda refresh on Friday. According to the company, less than 1% of queries are noticeably affected in the U.S. Worldwide, 1% are apparently affected.

Google told us earlier this month that there had not been another Panda update, after some webmasters suspected one, but that has obviously changed now.

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FYI Panda data refresh started rolling out on Friday. Less than 1% of queries noticeably affected in the U.S. & 1% worldwide

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2 minutes ago via web · powered by @socialditto

If you’ve been hit by the Panda update, remember, you can recover. Last year, Google put out this list of 23 questions to ask yourself about the quality of your content:

• Would you trust the information presented in this article?
• Is this article written by an expert or enthusiast who knows the topic well, or is it more shallow in nature?
• Does the site have duplicate, overlapping, or redundant articles on the same or similar topics with slightly different keyword variations?
• Would you be comfortable giving your credit card information to this site?
• Does this article have spelling, stylistic, or factual errors?
• Are the topics driven by genuine interests of readers of the site, or does the site generate content by attempting to guess what might rank well in search engines?
• Does the article provide original content or information, original reporting, original research, or original analysis?
• Does the page provide substantial value when compared to other pages in search results?
• How much quality control is done on content?
• Does the article describe both sides of a story?
• Is the site a recognized authority on its topic?
• Is the content mass-produced by or outsourced to a large number of creators, or spread across a large network of sites, so that individual pages or sites don’t get as much attention or care?
• Was the article edited well, or does it appear sloppy or hastily produced?
• For a health related query, would you trust information from this site?
• Would you recognize this site as an authoritative source when mentioned by name?
• Does this article provide a complete or comprehensive description of the topic?
• Does this article contain insightful analysis or interesting information that is beyond obvious?
• Is this the sort of page you’d want to bookmark, share with a friend, or recommend?
• Does this article have an excessive amount of ads that distract from or interfere with the main content?
• Would you expect to see this article in a printed magazine, encyclopedia or book?
• Are the articles short, unsubstantial, or otherwise lacking in helpful specifics?
• Are the pages produced with great care and attention to detail vs. less attention to detail?
• Would users complain when they see pages from this site?

Google didn’t say exactly that these are official guidelines, though many of them did reappear in Google’s recently launched Webmaster Academy.

Were you affected by this update? Let us know in the comments.

More Panda coverage here.