ENQUIRE implicitly allowed for either automatic or interactive query expansion, in that searchers could choose to remove or add to the candidate terms extracted by the system, or accept them without any changes. Term deselection, as opposed to explicit selection as implemented in the earlier GUI, is deemed to be less demanding for the user [18]. INSPEC searchers had slightly more opportunities for query expansion and used it more often than LBS searchers (24% and 18% respectively), but both groups were just as likely to expand their queries automatically as interactively. The take-up of the facility in both databases is almost double that reported in the first GUI project but less than in the Okapi at City Project, where a third of users expanded searches. More than half of expanded searches in INSPEC were fruitful and just over a third in LBS. Searches which were expanded automatically in LBS seemed to be more successful than those expanded interactively.
In summary, given the opportunity to interact, INSPEC users could build on the system's initiative and to improve their search further, but LBS users had less to work with at the outset and their own efforts to intervene appeared to be less fruitful than if they depended on the system. Overall the combined facility for both automatic and interactive query expansion provided by the ENQUIRE system was much more effective than the interactive version previously tested, and was also an improvement on the fully automatic facility first implemented.