The authors thank Ken Wilbur, Linli Xu, Max Joo, Sesh Tirunillai, Kathy Li, Jason Duan, Liye Ma, Samsun Knight, and the Marketing Science review team for thoughtful comments and suggestions and participants at Advertising Research Foundation Attribution & Analytics Accelerator 2022, Marketing Science Conference 2023, Interactive Marketing Research Conference 2024, Marketing Dynamics Conference 2024, and seminar participants at Amazon Ads, Dartmouth College, Indiana University Bloomington, London Business School, Northeastern University, Oklahoma State University, Western University, University of Arizona, University of Florida, University of Illinois Chicago, University of Illinois Urbana-Champaign, and University of Miami for feedback. This research was initiated while all authors were at the University of Houston, and the authors gratefully acknowledge the early support of Ed Blair and the Marketing Department at the Bauer College of Business.