• CNET News.com, Friday, May 30, 2008 10:03 AM

At the company's I/O conference, Google's Marissa Mayer, VP of search products and user experience, explained that the search giant refines the quality of its search results using a method called split A/B testing to show different versions of its search results to measure how users respond. For example, Google customarily shows 10 results per page, but when the results increased to 30 per page, people searched 20% less. This is because it takes twice as long to display those results, and speed matters. "As Google gets faster, people search more, and as it gets slower, people search less," Mayer said.

Just how exacting is this company? Even the white space around which Google pads its famous logo has gone through split A/B testing. "On the Web in general, (creating sites) is much more a design than an art," Mayer said. "You can find small differences and mathematically learn which is right." Even the copyright notice at the bottom of the Google homepage is there for a reason. "It's not there for legal reasons," Mayer said. "It's there as punctuation. That's it. (It tells the searcher) 'Nothing else is coming; please start searching now.'"

Not surprisingly, each and every search is a lot more complicated than it looks, involving 700 to 1,000 machines per search. And it will only get more complicated, Mayer said, envisioning future results pages being filled with "images, videos, and graphs--not a list of 10 URLs but as a holistic answer to your query."

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