Google is partnering with Nielsen so that companies that buy its Google TV Ads can find out how many people actually watch the ads.
Nielsen's metering devices are installed in a large number of households across the U.S., enabling the company to keep track of which TV programs are the most popular.
Now, Google will have access to Nielsen's demographic data from aggregated set-top boxes so advertisers can see what ads are effective and get additional aggregate information about the viewers, such as age and gender, according to Nielsen.
"This is the first time that advertisers and agencies will have this level of detailed measurement available in a single place and at such a large scale," a statement announcing the news on Wednesday said.
In addition to this multi-year strategic relationship, Google and Nielsen said they would explore other opportunities to work together "to measure online and other media." They did not elaborate.
Nielseninto the online world, measuring Web site traffic, streaming video, and video game usage, as well as monitoring buzz on blogs.
Meanwhile, Google is opening up its lucrative online advertising platform so that marketers can buy advertising not just on Web sites, but and radio, and in print.