Evaluation
Objective evaluation of search effectiveness has been a cornerstone of IR. Progress in the field critically depends upon experimenting with new ideas and evaluating the effects of these ideas, especially given the experimental nature of the field. Since the early years, it was evident to researchers in the community that objective evaluation of search techniques would play a key role in the field. The Cranfield tests, conducted in 1960s, established the desired set of characteristics for a retrieval system. Even though there has been some debate over the years, the two desired properties that have been accepted by the research community for measurement of search effective- ness are recall: the proportion of relevant documents retrieved by the system; and precision: the proportion of retrieved documents that are relevant.