Any comparison groups (e.g. Authoritative Lists, Peer Comparisons, Secondary Groups and Predefined Groups) you have previously created but have not accessed in 120 days are automatically deleted. This is due to the tremendous amount of data storage space such comparisons take up.

Please note, however, that ILL Analyses are the exception. They do not expire.

Visit OCLC's WorldCat Collection Analysis at http://www.oclc.org/collectionanalysis/.