The Quantity of the Quotation Index (QI) is defined by the number of links to this document in other sources. For more precise determination of a document importance not only the number of links to them, but a property of these links is important.
In the Internet IQ is a certain number inventorying the number of hyperlinks specifying the site and their Quotation Index. IQ is used by Yandex Company. The methodology of the IQ calculation is constantly refining. IQ directly affects the position of a site in the Yandex Catalog and indirectly affects the position of a site in search results. It's updated periodically.