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Collections Statistics is the place to go to find out the overlap between books in various collections and to troubleshoot problems with "missing books."
Collections are groupings within Your books that you create. Unlike in a real library, in LibraryThing a book can be "shelved" in more than one Collection. By default, all books you add are included as part of Your library unless you make changes using the Collections feature. Some Collections, like Wishlist and Currently Reading, have special properties, and more special features are planned for Collections. Collections is a powerful, but somewhat complicated tool. For more information, see the Collections help page.
The Collections Statistics page has two sections:
- Collections overlap
- Books not in collections
 Collections overlap
In this section you should see all of your Collections listed as headings. Every book must stay in at least one Collection. If something odd happens and you manage to remove a book from all Collections, then a "Lost and found" collection will be created to hold that book. For each Collection heading, the number of books is listed in parentheses. If any of the books in that Collection are also found in another Collection (overlap), then the overlap category is listed with the number of overlapping books in parentheses.
For example, let's say that you have 5 books in Your library that you've also added to your Favorites Collection. Under the Your library heading, it would show Favorites (5) and under the Favorites heading it would show Your library (5). What's more, you could click to get a view of your catalog showing only those 5 overlapping books.
 Books not in collections
These are the anti-collections! For each Collection, the number of books NOT in that Collection will be shown in parentheses. Click on the Collection name link to see a list of books NOT in that Collection. This feature is particularly useful for finding books you accidentally added to the wrong Collection and left out of, say, Your library.
 Notes and Frequently-Asked-Questions
 My books are missing! Where did they go?
There are two main reasons you might think books are missing from a Collection.
- You might be showing a different view of Your books than you think you are. In Your books (the catalog view), there's a button to the top left of the page with a folder on it; click on the button to change this to All collections, Your library, or whatever Collection you would like to see.
- You might have removed a book from a Collection. In Collections Statistics from Your profile, click on the Books not in collections link for Your library or whatever other Collection a book is missing from. This inverse link will list the books not in that Collection, and your book should be listed. If the book is listed, see the the Collections help page for more information on reassigning books to different Collections. The only way a book would be deleted completely is that you clicked the red X for that book. Even if you remove a book from all Collections, it won't be deleted, just filed into Lost and found.