Hope this helps for analyzing ranking and traffic changes. Only the changes right around these dates are likely to be caused by Panda. Links go to the thread where the discussion occurs.

Data Refresh = New website data only, no algorithm change

Jan 22,2013 [webmasterworld.com]
Nov 21, 2012 [webmasterworld.com]
Nov 6, 2012 [webmasterworld.com]
Sep 18, 2012 [webmasterworld.com] data refresh
Aug 20, 2012 [webmasterworld.com] data refresh
Jul 24, 2012 [webmasterworld.com] data refresh
Jun 25, 2012 [webmasterworld.com] data refresh
Jun 08, 2012 [webmasterworld.com] data refresh
Apr 27, 2012 [webmasterworld.com]
Apr 19, 2012 [webmasterworld.com]
Mar 23, 2012 [webmasterworld.com]
Jan 19-24, 2012 [webmasterworld.com] data refresh
Feb 26, 2012 [webmasterworld.com]
Nov 19, 2011 [webmasterworld.com] "minor" update
Oct 13, 2011 [webmasterworld.com]
Sep 27, 2011 [webmasterworld.com]
Aug 12, 2011 [webmasterworld.com]
Jul 23, 2011 [webmasterworld.com] ( our monthly Update thread)
Jun 16, 2011 [webmasterworld.com]
May 10, 2011 [webmasterworld.com]
Apr 11, 2011 [webmasterworld.com]
Feb 24, 2011 [webmasterworld.com]

[edited by: tedster at 4:35 am (utc) on Jan 28, 2013]