Yahoo and the online metrics firm comScore announced today their plans to jointly deliver better ad measurements for ads on Yahoo websites. The move will use comScore's verification platform to provide better data to marketers.

"Brands are reaching their audiences through multiple channels and need a consistent way to measure results across their campaigns," said Eric Lange of Yahoo.

The new service "provides advertisers with one place to buy, measure and analyze campaigns against all available data. That's something advertisers can't get anywhere else today."

Yahoo's online ad revenues has fallen and the company is trying to compete with Microsoft, Google and Facebook.