After almost 2 weeks of weird google ranking changes, google announced it now officially. Google has announced on their twitter account that there will be a new Google Panda Data refresh, making this version #24.
This data refresh has a noticeable impact 1.2% of English based queries according to Google.
New Panda data refresh rolling out today: 1.2% of English queries affected. Background: goo.gl/8Zqy1
— A Googler (@google) January 22, 2013