Access

[|ALA Equity of Access]


 * Access to information objects**


 * Intellectual access: find, identify, and select a work through information retrieval systems based on needs.
 * Physical access: select and obtain a copy of the information-bearing item.


 * Rules of bibliographic control**


 * Identifying all types of information objects as they are made available.
 * Identifying works contained within information objects or parts of them.
 * Systematically pulling together these information objects into collections and depositories.
 * Producing lists of information objects prepared according to standard rules of citation.
 * Providing name, title, subject and other useful access points.
 * Providing means of locating object.


 * Measurements in information retrieval -- precision and recall**
 * **Precision** is a measurement of the ratio of relevant documents to non-relevant documents in the search results. **Average precision** refers to the number of relevant documents at the top of the search results (in a relevance-ranked list).
 * **Recall**, on the other hand, is a measure of the number of relevant documents out of the whole document base that are returned by the search. A 100% recall would be a search that pulled every possible relevant document from the database; it might not be a 100% precise search, though, if there are false drops included in the returns along with all the relevant docs from the database.


 * Two approaches to bibliographic control are**
 * //catalogs//, which are a tool reflecting library’s collection and acting as access mechanism to resources beyond the library (a //union catalog// is a conglomerate catalog; a //shelf list// file arranged by call number and works best in very small collections)
 * and //indexes,// which are tools used to locate information within the //bibliographic universe// (the totality of published items). Indexes include explanatory materials — how to use — and can be unrelated to library’s catalog; not all materials in index will be available in library, but electronic indexes are often linked to the OPAC.


 * Principles of bibliographic control**

Arrangement
 * arbitrary doesn’t mean anything in relation to records (alphabetical)
 * meaningful order is significant to records (classified or subject)

Collocation and name authority control
 * similar materials gathered together
 * changing terminology/subj headings makes collocation difficult
 * syndetic structure: maintenance of linkages between terms (xref between old/new, general/specific)
 * field divisions (separate print catalogs/indexes for subject, author, title or ability to specify fields in electronic catalog/indexes)

Subject authority control
 * controlled vocabulary and controlled syndetic structure
 * Dublin Core doesn’t have subject field but lets user define field names (like w/XML) and vocabulary; helpful for internet cataloging initiatives

Depth and comprehensiveness
 * bibliographic record standardized (citation format, MARC record)
 * unit record differs among indexes (descriptors/identifiers, what fields included)
 * thesaurus links descriptors — broader, related and narrower terms