COMPARING BOOLEAN AND PROBABILISTIC INFORMATION-RETRIEVAL SYSTEMS ACROSS QUERIES AND DISCIPLINES

Whether using Boolean queries or ranking documents using document and term weights will result in better retrieval performance has been the subject of considerable discussion among document retrieval system use rs and researchers. We suggest a method that allows one to analyticall y compare the two approaches to retrieval and examine their relative m erits. The performance of information retrieval systems may be determi ned either by using experimental simulation, or through the applicatio n of analytic techniques that directly estimate the retrieval performa nce, given values for query and database characteristics. Using these performance predicting techniques, sample performance figures are prov ided for queries using the Boolean and and or, as well as for probabil istic systems assuming statistical term independence or term dependenc e. The variation of performance across sublanguages (used in different academic disciplines) and queries is examined. The performance of mod els failing to meet statistical and other assumptions is examined.