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Google tries tighter aim for Web ads

Search giant is, for the first time, testing how to use its deep reservoir of data about online behavior to aim ads at Web surfers. (From The New York Times)

Google, with its deep reservoir of data about online behavior gathered by tracking hundreds of millions of computers, is for the first time testing ways to use some of that data to aim ads at Web users.

Ads that a person sees on one Google search may be influenced by what was searched a few minutes earlier. Searching for "scuba," then something else, and then "vacations" could pull up ads for diving trips, for example.

This small but significant change in Google's strategy was discovered by Gene Munster, a securities analyst at Piper Jaffray, who this year started a series of tests looking at which ads were displayed in a series of queries on Google's search engine. Google assigns every computer that visits its sites a unique number--known as a cookie--and records searches and other activities in an unimaginably large file with those cookies.

The company previously said that it had not used any of that information to draw inferences about users for the purpose of selecting ads to show them.

Google changed its privacy policy a few years ago and warned users that it might capture personal information about them for reasons that include "the display of customized content and advertising." Last year, Google started looking at the immediately previous search when considering ads. Google did not need to use its cookies for this because Web browsers report the address of the previous site visited to the current site being visited. And in the case of a search, that address contains the search terms.

Nick Fox, a director of product management who looks after ads on Google's search site, said the company was now testing the use of more search queries in its ad targeting. He did not describe how it was doing that. But Internet experts said that it was most likely using its cookies.

Fox said that Google's approach was different from what Yahoo, AOL, and others call behavioral targeting. Those companies look at what a user did a few days earlier to show them ads about the same topic today. Google says it believes that search engine advertising is most effective if it relates to what the user has most recently searched for.

"We are trying to understand what the user is trying to do right now," Fox said. "In some cases, those queries are ambiguous, so you need a little more context."

Google's previous system of looking at a user's immediate past query was not useful enough, he said. "It is probably not just the previous query that matters," Fox said. "You want to know if the user is still doing the same thing. You wouldn't want to go back a month. You wouldn't want to go back a day. But you may want to go back two or three queries."

How data is used for advertising has become politically delicate. Many of the biggest companies on the Internet--Yahoo, AOL, and Microsoft--have bought advertising firms because they are convinced there is a lot of money to be made by tracking users' behavior. Although they say they have steps in place to protect users' privacy, the Federal Trade Commission is considering regulating ad targeting.

A critical factor in the debate is what Google, with its vast scale, does or may do with the data it has. Google controls two-thirds of the search market. It runs by far the biggest advertising network. Its DoubleClick unit is the biggest provider of ad technology to publishers and advertisers. Its toolbar is installed in many browsers, including every new Dell computer. And Google Analytics is gathering information from millions of Web sites.

Google is quick to point out that some of these systems are not connected to each other. And most of the information it gets is not what is generally considered to be personally identifiable, like a name or e-mail address. But once a user chooses to provide personal information to Google, perhaps by signing up for Gmail or Google Checkout, that information can be linked to much of the information that had been, until that time, collected anonymously.