NEW YORK: Ratings companies Nielsen and comScore have attracted high-profile clients for their online ad measurement systems as marketers seek to track ads effectively across multiple screens.

Starcom MediaVest Group and ZenithOptimedia, both part of Publicis Groupe, have opted for comScore's Validated Campaign Essentials system, while US network ABC backed Nielsen's Online Campaign Ratings.

ABC said Nielsen's product was "quickly emerging as the standard for online campaign measurement" and added that the deal with the measurement company would include the development of a new service covering mobile video ads, MediaPost reported.

"An increasing amount of our digital video viewing comes from apps on mobile devices, so the ability to understand who sees ads is crucial for our business," said Geri Wang, president of sales at ABC.

She added: "This trial with Nielsen is a significant next step in allowing us to help advertisers see the whole picture."

The move by Starcom MediaVest and Zenith is potentially significant, however, as the Wall Street Journal noted they spend around $32bn a year on ads in the US alone on behalf of brand owners such as Coca-Cola and Anheuser-Busch InBev.

Explaining its decision, Starcom said it was important that the comScore service was offered in more countries and also that it could collaborate with the digital research firm to create new measurement products.

"It's a multi-screen, mobile world and we need to be able to measure audiences fluidly and seamlessly," said Laura Desmond, SMG's chief executive officer.

"Traditional industry measures and players fall short on delivering the innovation we need for our clients," she added.

Data sourced from Wall Street Journal, MediaPost, ClickZ; additional content by Warc staff