Studies Question Yahoo's Index Size

Yahoo's claims that its search index now doubles Google's are being refuted after two separate tests were conducted by researchers at Google and the National Center for Supercomputing Applications, located at the University of Illinois.

Last Monday, Yahoo developer Tim Mayer claimed in the company's search blog that the most recent update to the search engine included "just over 19.2 billion web documents, 1.6 billion images, and over 50 million audio and video files."

However, John Battelle, a visiting professor at the University of California at Berkeley, reported that through his discussions with Google, he found that their scientists saw no change in the breadth of Yahoo's search results.

"There are some tantalizing examples one might expect would yield significantly different results between Yahoo and Google, given Yahoo's massive new size, but don't," Battelle wrote. "The math, in essence, seems not to be adding up."

Battelle and Google's suspicions were confirmed by NCSA on Monday, which said a user could still expect on average 167 percent more results through Google. Only in 307 of the 10,012 cases did Yahoo produce more results than Google did.

To test the search engines, the researchers created a script containing 135,069 words and would randomly pair two words. The number of results were then returned and logged.

"It is the opinion of this study that Yahoo's claim to have a web index of over twice as many documents as Google's index is suspicious," the NCSA researchers concluded.

"Unless a large number of the documents Yahoo! has indexed are not yet available to its search engine, we find it puzzling at Yahoo's search engine consistently returned less results than Google."