Google Keeps Tweaking Its Search Engine

Mr. Singhal is the master of what Google calls its "ranking algorithm" -- the formulas that decide which Web pages best answer each user's question. It is a crucial part of Google's inner sanctum, a department called "search quality" that the company treats like a state secret. Google rarely allows outsiders to visit the unit, and it has been cautious about allowing Mr. Singhal to speak with the news media about the magical, mathematical brew inside the millions of black boxes that power its search engine.

[...]

Until now, Google has preferred pages old enough to attract others to link to them.

But last year, Mr. Singhal started to worry that Google's balance was off. When the company introduced its new stock quotation service, a search for "Google Finance" couldn't find it. After monitoring similar problems, he assembled a team of three engineers to figure out what to do about them.

Earlier this spring, he brought his squad's findings to Mr. Manber's weekly gathering of top search-quality engineers who review major projects. At the meeting, a dozen people sat around a large table, another dozen sprawled on red couches, and two more beamed in from New York via video conference, their images projected on a large screen. Most were men, and many were tapping away on laptops. One of the New Yorkers munched on cake.

Mr. Singhal introduced the freshness problem, explaining that simply changing formulas to display more new pages results in lower-quality searches much of the time. He then unveiled his team's solution: a mathematical model that tries to determine when users want new information and when they don't. (And yes, like all Google initiatives, it had a name: QDF, for "query deserves freshness.") --Saul Hansell --Google Keeps Tweaking Its Search Engine (New York Times)