We're all guinea pigs in Google's search experiment

SAN FRANCISCO--When it comes to search quality, Google has a split personality.
Google uses a method called split A/B testing to measure exactly what changes it should make to its main search Web site--both to its famously Spartan search box and to the results it produces. With the approach, Google shows different versions of the pages to users and measures how they respond, said Marissa Mayer, vice president of search products and user experience, in a speech at the Google I/O conference here Thursday.

For example, Mayer said, the company wanted to find out how many search results to show users--the customary 10, or 20, 25, or 30? When asked directly, users said they'd like more results on a page, but testing showed otherwise.
Specifically, Google found that when the results increased to 30 per page, people searched 20 percent less overall, Mayer said. After much analysis of server logs, the company found it was because it took about twice as long to display the longer results list for the user, and speed matters.
"As Google gets faster, people search more, and as it gets slower, people search less," she said.
The same effect happened with Google Maps. When the company trimmed the 120KB page size down by about 30 percent, the company started getting about 30 percent more map requests. "It was almost proportional. If you make a product faster, you get that back in terms of increased usage," she said.

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