Comparative Evaluation of the Retrieval Effectiveness of Descriptor and Free-Text Search Systems Using CIRCOL (Central Information Reference and Control on-Line)
Final rept. 1 Apr 1970-1 Jul 1971
WESTAT INC ROCKVILLE MD
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The study compares the retrieval effectiveness of two alternative input and search systems in terms of such measures as recall, fallout, precision, and total retrieval. One system operates using manually indexed document files searched by controlled vocabulary while the other employs full- text input using natural language searching. Both systems are applied to a common data base and hardware. Operational information needs were used in the form of request statements from actual users. From these statements of need, search queries were formulated for both systems and recall estimates calculated using a recall base that was pre-specified by the request origninator. The queries were processed and total retrieval, fallout and precision ratios were calculated for both systems. The results indicate that the two systems perform at approximately the same level of effectiveness, although estimated average total retrieval was found to be slightly greater for free-text searching than for descriptor searching at all levels of recall.
- Information Science