In the continuing debate on measuring online advertising, Starcom says it has found a way to track not only the ad that people eventually click on but also the impressions leading up to that final click, according to AdAge.

For example, a rich-media homepage takeover - despite being the more effective unit - may incorrectly be assigned less value than a simple button farther down a cluttered page, simply because the latter was the ad the user ultimately clicked on. The new system will allow marketers to see how effective the whole online marketing mix is.

Starcom has dubbed its solution "multiple-attribution protocol" and hopes it will determine the right combination of ads to increase sales. More simply, it's a system that can in real time monitor the mix of search and display ads responsible for a conversion.

"You've got to remove the search, display and web-site reporting silos," said Mike Zeman, VP-media director at Starcom. "And you've got to throw out the myopic most-recent-exposure reporting approach."