Academic journal article Library Resources & Technical Services

"Garbage" in, "Refuse and Refuse Disposal" Out: Making the Most of the Subject Authority File in the OPAC

Academic journal article Library Resources & Technical Services

"Garbage" in, "Refuse and Refuse Disposal" Out: Making the Most of the Subject Authority File in the OPAC

Article excerpt

Subject access in the OPAC, as discussed in this article, is predicated on two different kinds of searching: subject (authority, alphabetic, or controlled vocabulary searching) or keyword (uncontrolled, free text, natural language vocabulary). The literature has focused on demonstrating that both approaches are needed, but very few authors address the need to integrate keyword into authority searching. The article discusses this difference and compares, with a query on the term "garbage," search results in two online catalogs, one that performs keyword searches through the authority file and one where only bibliographic records are included in keyword searches.

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Early catalog use studies indicated that most searching in a catalog was for known items (Gochrane 1985; Bodoff and Kambil 1998). With the advent of computerized catalogs, subject searching came to be the predominant target for users (Drabenstott and Vizine-Goetz 1994; Hildreth 1997; Matthews 1997; Bodoff and Kambil 1998). Early OPACs provided for subject searching only by the subject heading of the bibliographic record. However, keyword searching came into use almost immediately, with most OPACs allowing for word searches in subjects, titles, and notes. A decade ago, the big question was whether keyword searching alone would suffice for subject access. The conclusion was a resounding "no!": controlled vocabulary (authorized terms) was absolutely necessary--but only if the relevant cross references were also supplied (Frost 1989; Jamieson, Dolan, and Declerck 1986; Marner 1993; Micco 1991; Smith 1991; Tillotson 1995). Users could not be expected to know the authorized subject term in order to perform subject searches. Markey (1988) suggested loading the entire Library of Congress Subject Headings (LCSH) into the OPAC to overcome this deficiency. Most libraries today, however, make do with authority records and cross references for headings actually used in the bibliographic records in their own catalogs.

Subject searching in OPACs continues to be problematic (Hildreth 1997; Matthews 1997; Yee and Layne 1998). For average users, a subject is just anything they wish to know "about." The searcher has little or no understanding of the distinction in a catalog between "keyword" searching and "subject" searching. Most catalogs use the term "keyword" to mean "free text" and "subject" to mean "controlled vocabulary" searching. Nor does the user understand that subject searches are based on left-anchored string searching, while keyword searches are generally based on words within a subject, title, or elsewhere in the bibliographic record (Yee and Layne 1998). Moreover, the average user does not understand that subject searches are based on controlled vocabulary used in the bibliographic record (for instance, LCSH) and represented in an authority file (Markey 1988; Cherry 1992; Drabenstott 1998; Smith 1991). Greenberg (1997) notes the failure of most OPACs even to refer to LCSH as the source of subject headings. Matth ews (1997) identifies that even a keyword search of LCSH authorized headings (excluding cross references) will retrieve records only about 50% of the time.

In the typical online catalog, the distinction between keyword and controlled vocabulary subject searching, although present, is almost completely opaque to the user. Whether OPAC users actually choose "keyword" or "subject" as their search mode, the plain fact is that both end up being natural language searches in the absence of any guidance concerning the subject heading structure. If the term entered in a subject search happens to be the first word of the authorized form, then the user will likely find relevant citations. If the term entered in a subject search also happens to be the first word of a cross reference in a catalog that displays cross references, then the user will also be correctly directed. However, if the term entered in a subject search is a word within a subject heading or cross reference, then the user misses the authority control structure of the catalog. …

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