You’ve read all of your free items this month. To register, get added benefits and unlimited access to articles, Become a Member. Already a Member? Sign in. Advertising Age Article Abstract OPA Ad Effectiveness Study: It's Not That Black and White Most Clients Buying Ad Networks Are Focused on Different Metrics By Rajeev Goel, Published on August 14, 2009 2 Want more Access, Content & Connections? Upgrade to Membership. We are glad you are enjoying Advertising Age. To get uninterrupted access and additional benefits, become a member today. Register Now Already a member? Log in.