Expected search length: A single measure of retrieval effectiveness based on the weak ordering action of retrieval systems

摘要: A measure of document retrieval system performance called the “expected search length reduction factor” is defined and compared with indicators, such as precision recall, that have been suggested by other workers. The new based on calculations expected number irrelevant documents in collection which would to be searched through before desired relevant could found. Its advantages are: (1) it provides a single index for property attempts measure; (2) allows gradations status, mathematical concept “weak ordering”; (3) evaluates relative random searching; (4) takes into account amount material requester.