Constructing a true LCSH tree of a science and engineering collection by Charles-Antoine Julien, Pierre Tirilly, John E. Leide and Catherine Guastavino.
The Library of Congress Subject Headings (LCSH) is a subject structure used to index large library collections throughout the world. Browsing a collection through LCSH is difficult using current online tools in part because users cannot explore the structure using their existing experience navigating file hierarchies on their hard drives. This is due to inconsistencies in the LCSH structure, which does not adhere to the specific rules defining tree structures. This article proposes a method to adapt the LCSH structure to reflect a real-world collection from the domain of science and engineering. This structure is transformed into a valid tree structure using an automatic process. The analysis of the resulting LCSH tree shows a large and complex structure. The analysis of the distribution of information within the LCSH tree reveals a power law distribution where the vast majority of subjects contain few information items and a few subjects contain the vast majority of the collection.
After a detailed analysis of records from the McGill University Libraries (204,430 topical authority records) and 130,940 bibliographic records (Schulich Science and Engineering Library), the authors conclude in part:
This revealed that the structure was large, highly redundant due to multiple inheritances, very deep, and unbalanced. The complexity of the LCSH tree is a likely usability barrier for subject browsing and navigation of the information collection.
For me the most compelling part of this research was the focus on LCSH as used and not as it imagines itself. Very interesting reading. A slow walk through the bibliography will interest those researching LCSH or classification more generally.
Demonstration of the power law with the use of LCSH makes one wonder about other classification systems as used.