Brett Hollenbeck
Associate Professor of Marketing
UCLA Anderson School of Management
Brett Hollenbeck is an associate professor of marketing at UCLA Anderson School of Management, where he works on empirical industrial organization and quantitative marketing. He co-wrote a study of how web searching and browsing changed after people adopted ChatGPT and other chatbots, and earlier studied the market for fake online reviews.
Presenting the Chatbot Adoption Study
"Patterns suggest that LLMs act as substitutes, not complements, to traditional online activities," read the key-findings slide of the deck Hollenbeck presented at the Toulouse Digital Economics Conference in January 2026. The paper, written with Nicolas Padilla, H. Tai Lam and Anja Lambrecht, was accepted at Management Science later that year.
The team followed the desktop browsing of more than 1 million U.S. users in the Comscore panel and found 2,041 who started using ChatGPT, Bing Chat or Bard in the tools' first year. For about 20 weeks their searching did not change. Then searches in traditional engines fell 21.7% against pre-adoption levels, and visits to the smallest websites fell 41.8% while the top 500 sites showed no significant decline, the UCLA Anderson Review reported.
Fake Reviews and Online Reputation
Much of Hollenbeck's earlier work examined how sellers try to game online reputation. "The Market for Fake Reviews," with Sherry He and Davide Proserpio, appeared in Marketing Science in 2022, and a companion paper in the Proceedings of the National Academy of Sciences used network structure to detect fake review buyers on Amazon. The three also wrote "How Fake Customer Reviews Do and Don't Work" for Harvard Business Review in 2020.
Other papers covered how online reputation systems reduced the value of chain affiliation, advertising strategy when reviews are visible, and the effect of Apple's App Tracking Transparency on e-commerce firms, forthcoming in Management Science.
From the Treasury to UCLA Anderson
Before his PhD in economics at the University of Texas at Austin, Hollenbeck was an economist in the Office of Tax Policy at the U.S. Department of the Treasury and a research fellow at the U.S. Chamber of Commerce. He holds a BS in economics and a BA in political science from George Washington University. At Anderson he teaches Customer Assessment and Analytics to MBA students.