corrupt statistics

My statistics have been corrupted lately ir at least I think that is the case. Every week I run the following command from a stored proc: executes this command
"analyze table schema.table_name compute statistics for table for all indexed columns for all indexes"
this runs against all user defined tables across all schemas

I am assuming corruption because performance becomes abysmal and explain plan shows problems after I run statistics manually against the individual tables, I see the normal and fast explain plan. This has occurred three times in five weeks.

Can I query the database somehow to see if the statitics are correct or finished abnormally, the Stored proc states it completed succesfully.

Would I be better to delete statistics prior to analyzing?

Where can I read good information regarding the indexes and datapages. I am a former Sybase DBA and have to relearn the basics of how data is stored in the database data pages leaf pages, what the index creations really do i.e reorganing data. I feel really stupid lately please help Received on Fri Aug 23 2002 - 09:45:30 CDT