When Query Expansion Fails

The effectiveness of queries in information retrieval can be improved through query expansion. This technique automatically introduces additional query terms that are statistically likely to match documents on the intended topic. However, query expansion techniques rely on fixed parameters. Our investigation of the effect of varying these parameters shows that the strategy of using fixed values is questionable

Questioning Query Expansion: An Examination Of . . .

In information retrieval, queries can fail to find documents due to mismatch in terminology. Query expansion is a well-known technique addressing this problem, where additional query terms are automatically chosen from highly ranked documents, and it has been shown to be effective at improving query performance. However, current techniques for query expansion use fixed values for key parameters, determined by tuning on test collections. In this paper we show that these parameters may not be generally applicable, and more significantly that the assumption that the same parameter settings can be used for all queries is invalid. Using detailed experiments with two test collections, we demonstrate that new methods for choosing parameters must be found. However, our experiments also demonstrate that there is considerable further scope for improvement to effectiveness through better query expansion

Examining the pseudo-standard web search engine results page

Abstract Nearly every web search engine presents its results in an identical format: a ranked list of web page summaries. Each summary comprises a title; some sen-tence fragments usually containing words used in the query; and URL information about the page. In this study we present data from our pilot experiments with eye tracking equipment to examine how users interact with this standard list of results as presented by the Aus-tralian sensis.com.au web search service. In partic-ular, we observe: different behaviours for navigational and informational queries; that users generally scan the list top to bottom; and that eyes rarely wander from the left of the page. We also attempt to correlate the number of bold words (query words) in a summary with the amount of time spent reading the summary. Unfortu-nately there is no substantial correlation, and so stud-ies relying heavily on this assumption in the literature should be treated with caution