Should ALL Advertising Should Be Measured on Impressions?A diverse group of experts from advertising agencies, media, clients, and researchers, as well as advertising scholars discuss the transformation of the industry toward impression-based advertising. The potential impacts are immense – likely changing everything about pricing, reporting, evaluation, and more. This shift will impact more than half a trillion dollars ANNUALLY in the coming years!Cross-platform advertising – involving multiple types of media – is becoming the norm. But that approach requires a much different perspective on advertising measurement. Old metrics are less valuable in the new world. Advertising Impression Measurement focuses on the challenges and opportunities of the change to impression-based advertising.The output of these discussions is a consensus that the advertising world needs to move to impression-based advertising measurement. But there are at least 15 important challenges to moving forward. To help conceptualize the overall system and related factors, an Advertising Process Model (APM) is proposed as a broad representation of the advertising eco-system.