Useful statistics references…
The Basics
sp_helpindex (Kimberly L. Tripp)
Statistical maintenance functionality (autostats) in SQL Server
Statistics Used by the Query Optimizer in Microsoft SQL Server 2005
Statistics Used by the Query Optimizer in Microsoft SQL Server 2008
Statistics Changes in SQL Server 2012
SQL Server 2012 Partitioned Index Default Sampling Algorithm Changes (Joe Sack)
Behavior Changes to Database Engine Features in SQL Server 2012
Statistics and Performance
Using Statistics to Improve Performance (MSDN)
Filtered Indexes/Statistics
Filtered Indexes – What You Need to Know (Michelle Ufford)
Filtered indexes and filtered stats might become seriously out-of-date (Kimberly Tripp)
A Case of Using Filtered Indexes
Using Filtered Statistics With Partitioned Tables (SQLCAT)
The Kitchen Sink
How are auto created column statistics named (Paul Randal)
Changes to automatic update statistics in SQL Server – traceflag 2371
