THESAURUS CONSTRUCTION: GROUND WATER Madely du Preez

Controlled vocabularies Two indexing languages: Natural language Controlled vocabularies Examples of controlled vocabularies: Thesauri Ontologies Taxonomies folksonomies

Definitions INS3707 Study guide definition: A thesaurus is a systematic, organised aid which can assist indexers and users of IOAR systems to identify relationships and preferences between terms in order to index and retrieve documents National Information Standards Definition: A thesaurus, for the purpose of this standard, is a controlled vocabulary of terms in natural language that are designed for post coordination. The need to control the formation and use of terms stems mainly from two basic features of natural language, namely synonyms (different terms representing the same concept) and polysemes or homographs (terms with the same spelling representing different concepts).

Characteristics Alphabetically and hierarchically structured Indicate variety of indexing terms Includes references to preferred terms Indicates relationships among terms

Hierarchical relationships Broader to narrower terms BT Transport NT Road transport Air transport Shipping Narrower terms can also be broader terms: BT Road transport NT Buses Motor cars Trucks

Equal relationships and scope notes E.g. buses, motor cars, trucks Includes scope notes: “A Scope Note is a brief statement of the intended usage of a Descriptor. It may be used to clarify an ambiguous term or to restrict the usage of a term. Special indexing notes are often included.” (Eric Thesaurus Fact File)

Types of Thesauri General or multidisciplinary thesauri, e.g. Eric and ISAP thesauri Thesauri describing specialised collections can be multidisciplinary: art collections Thesauri for specialised collections: INIS for Nuclear energy information

Purpose of thesauri in information retrieval Used to describe contents of a document Information retrieval systems: Identify terms relevant to an information need Narrow information searches Ensures the retrieval of information in an IRS Promote a general idea of a subject field A semantic map of the interrelationships between terms Provide definitions for terms

Indexing terms INDEXING TERM Preferred terms Non-preferred terms (used for) Non-preferred terms (use)

Typical thesaurus entry INDEXING TERM SN (scope note) UF (used for) BT (Broader term) NT (Narrower term) RT (Related term)

EXAMPLE BREAD SN A staple food made from flour or meal mixed with other dry and liquid ingredients, usually combined with a leavening agent, and kneaded, shaped into loaves, and baked. BT Staple food RT Rice NT Ingredients Rye bread whole-wheat bread

Typical thesaurus entry (2) The nature of the indexing term determines the relationship Not every indexing term has a relationship with other terms – they are orphan terms Synonyms: choose one and indicate preference as follows: INDEXING TERM U (Use) Example: Leavening agent U YEAST

Indexing terms Scope notes Use scope notes to Indicate a series of subjects to be covered To give instructions to indexers To explain terms which have the same spelling but different meanings (homonyms) Not all indexing terms require scope notes

Equivalent relationships between indexing terms leavening agent U YEAST YEAST UF leavening agent RECIPROCAL ENTRY

Hierarchical relationships between indexing terms STAPLE FOOD NT Bread BREAD BT Staple food RECIPROCAL ENTRY

Relationships between indexing terms Nonhierarchical / equivalent relationships BREAD RT Rice RICE RT Bread Reciprocal entry

My Thesaurus BREAD BT Staple food RT Rice FLOUR BT Ingredients RT Yeast INGREDIENTS NT Flour Yeast Leavening agent U YEAST RECIPES RICE BT Staple food RT Bread STAPLE FOOD NT Bread Rice YEAST UF Leavening agent BT Ingredients RT Flour

Guidelines for formulating thesaurus entries Nouns and noun phrases Distance learning Use adjectives as indexing terms in exceptional cases Miniature sizes ; portable devices Avoid adverbs and verbs Book evaluation not evaluation of books Singular vs plural form Nouns for tangible objects that can be counted – plural: dogs, cats Non countable nouns – singular: sugar Spelling Colour vs color Punctuation Letters (alphabet) / Letters (correspondence) Multicultural societies not multi-cultural societies Abbreviations SADEC / Southern African Development Community Compound terms: Dried fruit; municipal engineering; corporate bodies

ACTIVITY Construct a thesaurus Age (of water) Aquifers Boreholes Drilling Geohydrology Hydrology Hydrogeology Ground water Ground water contamination Ground water management Groundwater Pumping tests Recharge Seepage Springs Sustainable yield Unsaturated zones Water tables Wells Yield

ANY QUESTIONS?