Comparison of manual and online retrospective searching for agricultural subjects

To investigate the value of externally available computer‐based bibliographic retrieval services in agriculture, 100 retrospective searches in response to real requests for information were carried out by computer. Seventy‐five of these were paralleled using conventional manual methods and the results were analysed and compared for efficiency, cost and staff time required. The databases most frequently used were CAIN (now AGRICOLA), BIOSIS and Chemical Abstracts Condensates (searched online using Lockheed Dialog), and Medline. Online searches took one‐sixth of the staff time required for manual searching and cost much the same. Online searches tended to have higher relative recall and lower precision than manual searches of the same database. The differences in performance are due to the different entry points available in the printed and machine‐readable forms of a database. Detailed knowledge of these will enable a choice to be made of the more efficient method of searching when both manual and online searching of a database is possible. Online searches were well received by users and their use could increase the output of library and information staff engaged in retrospective searching.