Outline of Cultural Materials

The Outline of Cultural Materials (OCM) is a standardized subject classification system designed primarily to categorize information about social and cultural life. The OCM can be used not only for organizing and indexing a wide variety of databases and collections, but also as a finding aid or searching tool.

The OCM was first developed by George P. Murdock and colleagues in the 1930s at Yale's Institute of Human Relations as part of the development of the Cross-Cultural Survey, a database of ethnographic information designed for scholarly research into cultural and social life across a worldwide sample of societies. The database continued to be developed by the Human Relations Area Files, which became a separate organization in 1949. The HRAF Collection of Ethnography, commonly referred to as the "HRAF files", has served as the basis for a wide variety of cross-cultural studies. Originally in paper and then microfiche, the first full-text electronic version of the eHRAF Collection of Ethnography was produced on CD-ROM in 1995, followed by the first online version in 1997. Human indexing with OCM subject identifiers at the document, page, and paragraph level of every text in the eHRAF databases remains the defining feature of the eHRAF databases today. A powerful tool for cross-cultural research, the meticulous paragraph-level indexing allows researchers to rapidly find relevant cultural materials.

Beyond its use in the eHRAF World Cultures and eHRAF Archaeology databases, the OCM can be used for many purposes within and beyond anthropology, such as subject-indexing field notes or museum collections. For example, the American Anthropological Association uses HRAF's OCM taxonomy to facilitate searching across AAA publications, meetings, the Open Anthropology Research Repository and member profiles. HRAF maintains the OCM in digital format in an information retrieval thesaurus structure. As such, in addition to being a classifying system, it is also a terminology cross-referencing system.

Keep in mind that OCM subjects are almost always broader than any keyword. For example, imagine that an artifact or file being cataloged using the OCM represented "monotheism". The OCM category Spirits and Gods would best fit this purpose. Spirits and Gods is part of a broader category, Religious Beliefs. This indicates that the OCM is organized as a two-level hierarchy, Religious Beliefs being the broader category and Spirits and Gods being the narrower one.

When used for indexing and searching collections, the hierarchical thesaurus organization of the OCM allows one to either broaden (maximizing recall) or to narrow (maximizing precision) the focus. If you choose categories higher up in the hierarchy, all the descendants of the category and its subcategories will also be included, thus increasing recall. If you choose categories further down in the hierarchy, only those chosen narrower categories and their descendants, if any, will be included, thus increasing precision.

Using this site

If you search for and click on a subject – e.g. Spirits and Gods – the subject category page will direct you to both the broader category; related subjects in the OCM that are not part of the hierarchy; a scope note; and a list of non-preferred terms. You may also browse OCM subjects by A-Z index or Hierarchical Display to find and explore subject categories.

In brief, the OCM subject category (or concept) is the fundamental building block of the OCM thesaurus. The OCM subject category has the following parts:

  • a numeric identifier, also called OCM code
  • a preferred term
  • a broader category with corresponding Broader Term and broader term identifier
  • a list of narrower categories with their corresponding Narrower Terms and narrower term identifiers
  • a list of non-preferred terms, also called Used Fors (This functions much like an index in a printed text.)
  • a Scope Note describing the scope of the material that is indexed with this category

Terms of Use

Human Relations Area Files, Inc. (HRAF) reserves exclusive rights to the title "Outline of Cultural Materials" and its contents. Should you wish to license the OCM for reuse or to modify its contents in any way, permission must be granted by HRAF. For the full Terms and Conditions and to submit a request, contact hraf-support@yale.edu.

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