Will Google Make ComScore, Nielsen Squirm?

Google launches a Web site measurement tool for advertisers and publishers that could compete with ComScore and Nielsen.

Google has about 10 years of analyzing data under its belt, figuring out search trends to help it sell its vaunted keyword advertising platforms.
Now that we're ensconced firmly in this rabid Web 2.0 era, where traffic is more competitive and precious than ever for advertisers and content publishers alike, Google is using its iterative knowledge to help others.
The company today issued Ad Planner, a free research and media planning tool that helps advertisers find site publishers with which they otherwise might not be familiar. Here's Google's mock-up of a campaign viewed through the Ad Planner lens.
Simply, advertisers and publishers can enter demographics and sites linked with their target audience and the tool will return information about sites on and off the Google content network that their audience is likely to visit.
This practice is very important to helping advertisers and publishers better connect with and target ads to their audience. Google said in a blog post Ad Planner will let users go granular by counting related searches for a particular site, or get aggregate statistics for the sites they've added to a media plan.
It's also the type of tool that may make ComScore and The Nielsen Company employees go a touch pale. ComScore and Nielsen provide similar stats, albeit via panels or surveys. Google has the benefit of leveraging its search results and third-party networks to figure out where people are going online.
Now that Google is providing a free tool, will ComScore's and Nielsen's businesses be threatened? I've put in e-mail queries to both vendors for comment and will update if I hear something substantive.
John Battelle was right to ask the question, but he's also right in wondering whether or not folks will use Ad Planner because Google makes it.
You know, it's that whole trust factor.

While Google said Ad Planner users can create media plans and export them to a .csv file, which can be opened in most spreadsheet applications, it also invites them to export their plans to Google's DoubleClick MediaVisor, which helps with media planning, buying and campaign management.
Do ad people and publishers want DoubleClick storing info about their media and campaign plans? Some might not mind, but for those jumping on the Google-knows-too-much-about-my-business bandwagon, I'm not so sure they will be comfortable practicing this.
Google is being careful early, offering Ad Planner by invitation only. The results, in terms of user testimonials, will bear watching.
Incidentally, the tool comes just days after Google pulled the trigger on Google Trends for Websites, a version of its popular traffic measuring tool to see how trafficked Web sites are.
The service, which emphatically does not search Google's sites, also compares and ranks site visitation across geographies and related Web sites and searches.