Top results of search engines are showing more and more differences

A recent study of Google, Yahoo, Windows Live and Ask delivered the same top result only 3.6 percent of the time. The search engines agreed more often in a study two years ago, in which the top result matched all four engines on 7 percent of queries.

The four never delivered the same top three results. Fewer than 1 percent of first-page results were shared by all four sites. "These differences contradict any notion that all search engines are the same and that searching one engine will yield the absolute best results of the web," the paper states.

The research spurred an executive with Ask.com to discuss the importance of knowing the strengths and weaknesses of each search tool, even for users who search only one engine each time they need information.