Catalog information and text as indicators of relevance

The indicativity of a type of catalog information (or catalog field) is intended as a measure of how well the information in the field conveys the contents of the document it represents. In the experiments reported here, indicativity is measured for several catalog fields by comparing users' evaluations of the relevance of documents on the basis of the information in a given field with their judgments on the basis of full text. A small but statistically significant increase in indicativity is found as the length of a catalog field (as measured by the number of different content‐word stems) is increased. The title field is found to have an indicativity of 0.64; matching subjects, 0.67; subjects, 0.70; abstract, 0.73. Despite the relatively small gain in indicativity for the longer fields, users value the longer fields highly for determining relevance if one judges by the amount of time they spend on them. Support for the hypothesis that the indicativity measure does not fully reflect the value of the fields is developed. Thus, the question of the cost effectiveness of the longer fields is unresolved. Other aspects of catalog field utility studied under the Project Intrex equipments are also reported.