HelpThing was written by members like you, with some help from LibraryThing staff.
View a list of all of the HelpThing topics.
The first rule of HelpThing is "be bold!" If you can add or edit it, go ahead. We also have a HelpThing Style Guide.
Your "Fun Statistics" page does some summarizing and calculating based on all of the books in your library.
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 Library Statistics
 Number of books
 Number of distinct works
LibraryThing groups editions and variants of the same book into "works", so that whether you have the Signet or the Dover Edition of Alice in Wonderland, you're linked to other people who have it. Many people have multiple copies of the same work in their library - two translations of The Odyssey, for example. This number tells you how many different works you have.
If this number is lower than your total number of books, clicking on the link at the bottom of this section will take you to a page that lists which of your books are duplicated. This can be a good place to check for books you may have inadvertently cataloged twice, as well as books that are incorrectly combined.
 Median/mean book obscurity
Measures how many people have your books. Basically, the lower your numbers are, the more obscure your collection is.
Take a given book - Guns, Germs, and Steel, for example. That book has 1,355 members who list it in their library. If you had only one book in your library, and that book was Guns, Germs, and Steel, your book obscurity would be 1,355 mean and 1,355 median.
Most of the time, however, you have more than one book. In that case, it provides an AVERAGE number. The most familiar type of average is the 'mean'. So, if you have the following three books in your library: Guns, Germs, and Steel (1,355 members), Save Me the Waltz (17 members), and Maori Myth and Legend (4 members), your mean book obscurity is 1,355 + 17 + 4 divided by 3. This is 458.7.
'Median' is a way of doing an average that works a little differently. The mean of 458.7 seems a little wrong, skewed high by that one really popular book. A median, by contrast, looks at the middle number in the set - in this case, 17. So the obscurity number would show up as "17/458.7 Median/mean book obscurity".
 Tag Statistics
Gives a count of how many total tags you've used, how many books you've used at least one tag on, and the average number of tags per book.
Lists of the books in your catalog, both by Language, and Original Language. These fields are typically pulled from the library records when you add books, and are editable on the Edit Books page, as well as in your catalog. Clicking on a language will bring up a catalog view of your books in that language.
 Cataloging sources
Counts which library source was used when adding books.
 Vous et nul autre
A list of books that you share with only one other member. This heading is from the French phrase Vous et nul autre, commonly used on poesy rings. The 'you' refers to the person with whom you share the book; the best way to think of it is probably "(I share this book with) you and none other". Clicking on the user name will take you to their profile; clicking on the book title will take you to its work page.
If you want a list of books that are unique to your library, click on the blue heading of the "Shared" column in your catalog to sort by your most-shared books, then click again to bring your least-shared books to the top.
How much do you like your books? Calculates an average rating of all of the books in your catalog, as well as a bar graph of the frequency with which you give out various ratings.
This graph gives a bar graph by decade of the publication date of your library, as well as a calculation of the average age of your books. This information is pulled from the "Date" column in your catalog, which by default is the publication date of your edition, NOT the original publication date of the work. Some users have manually filled in the "Date" column for all of their books with original publication date; in their case, this graph represents the age of their works, not their books.
 Entry Dates
A graph by month of when you added books to your catalog. Most members will have a spike in their first month. Once your cataloging is done, if you catalog new books as you acquire them, this graph can be a useful (if scary!) way to track your acquisition habits.
 Review Date
A graph by month of when you have written reviews. If you write a review for every book you read, this graph can be used to track your reading progress.