The Wall Street Journal reports that research company Nielsen is working on a new measurement service that would offer advertisers and website publishers a new stream of data to improve audience measurement for online advertising. As with TV ratings, the new service requires the participation of media outlets - in this case Web portals and other sites - and the firm has reportedly lined up Facebook as a participant. Other websites are expected to join as it moves out of the testing phase.

The new stream of data would be an "online GRP," which is short for Gross Rating Points - a formula that measures the reach and frequency of an ad, a method that has been used by the TV business for decades. To get the new data, Nielsen will blend its demographic panel data with information from participating online companies about the people seeing a particular online ad, according to people involved in the research.

Information will vary from website to website, but in general it might indicate the age group and sex of a particular web surfer and maybe even location. However, only anonymous data will be given to Nielsen for the service, according to several people involved in the process.

Marketers often use site traffic as a gauge when they decide to buy Internet display ads - the ads that include graphics and text and appear alongside the border of the page. But traffic alone isn't a perfect indicator of an ad's effectiveness. When people click on the ads, their specific actions can be tracked. But display ads are clicked on just a fraction of the time. That leaves room for an additional layer of measurement.

Media buyers say having an online GRP has the potential to give marketers a way to do apple-to-apple comparisons of media. Having the information, they say, could lead to advertisers shifting more of their ad budgets to the Internet from other media like television.