A Study of Overlap and Duplication among Children's Collections in Selected Public and Elementary School Libraries

Abstract

Overlap (when two libraries own the same title) and duplication (when one library has more than 1 copy of a book) in children's collections were measured in two elementary school libraries and the public library in each of four Illinois communities (population approximately 30,000). Two hundred book titles were randomly selected from the shelflists of the libraries and lists were compiled of magazines, science filmstrips, and fiction sound recordings. The relationship between collection size and overlap is linear and positively correlated. There is less overlap between two school libraries than between a school and a public library. As titles are listed in more selection aids, those titles are included in more library collections. Although there is little duplication, those titles included in the collections of more than one library are more likely to be duplicated in a particular library. The patterns of overlap and duplication detected for books are also present in the audiovisual materials studied.