OCR data, covering reach, frequency and gross rating points (GRP) measurment, will be used as the basis for determining how well AOL has delivered adverts to the desired target audience.

The partners says that this is the first time that online GRPs based on audience demographics have been used for advertiser guarantees on the web. Typically, clicks and impression counts are used.

Ran Harnevo, senior vice president at AOL Video, said: “As marketers and advertisers increasingly shift dollars from traditional TV advertising to the web, partnering with Nielsen puts AOL in a unique position to offer a more cost-effective mechanism for reaching targeted audiences and a better or equal brand lift, reach and recall.”

OCR was launched in August 2011 with aim of providing a form of measurement for online advetising that would be comparable to its TV equivalent.

The system works using pixel-tracking, so that when a particular display or video advertisement is shown in a browser its embedded tag pings Nielsen’s servers, which in turn ping a call to the web user’s browser to check whether they are a Facebook user. If a Facebook cookie is found, this triggers a call to Facebook which can then assign age and gender information for the user who encountered that ad tag.

At the end of each day Facebook delivers to Nielsen aggregate-level reports for each ad tag containing reach and frequency information in anonymous age and gender buckets. The ad tags are decrypted by Nielsen and performance reports are sent to advertisers.

In February Nielsen signed a major deal with Unilever to provide online campaign ratings for all its online advertising in the US for a 12-month period.