Calendrier du 01 avril 2019
Roy Seminar (ADRES)
Du 01/04/2019 de 17:00 à 18:30
Salle R1-09, Campus Jourdan, 48 boulevard Jourdan, 75014 Paris
HERRERA Helios (Warwick)
The Market for Product Reviews
écrit avec Jacob Glazer and Motty Perry
We propose a model of product reviews with honest and fake reviews in order to study the value of information provided on platforms like TripAdvisor, Yelp, etc. In every period, a review is posted which is either honest, i.e., it reveals the reviewer’s true experience with the product/service, or fake, i.e., it is fabricated in order to manipulate the public’s beliefs. We establish that the equilibrium is unique and derive a number of robust and interesting results. While fake agents are able to manipulate the public’s beliefs, aggregation of information takes place as long as some of the reviews are honest. We demonstrate that some of the mechanisms currently used to filter out fake reviews can be harmful.
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Régulation et Environnement
Du 01/04/2019 de 12:00 à 13:00
salle R1-13, campus Jourdan, 75014 Paris
DECAROLIS Francesco (Bocconi)
From Mad Men to Maths Men: Concentration and Buyer Power in Online Advertising
écrit avec Gabriele Rovigatti
This paper analyzes the impact of intermediaries concentration on the allocation of revenues in online platforms. We study sponsored search - the sale ad space on search engines through online auctions - documenting how advertisers increasingly bid through an handful of specialized intermediaries. This enhances automated bidding and data pooling, but lessens competition whenever the intermediary represents com- peting advertisers. Using data on nearly
40 million Google’s keyword-auctions, we first apply machine learning algorithms to cluster keywords into thematic groups serving as relevant markets. Then, through an instrumental variable strategy, we quantify a negative and sizeable impact of intermediaries’ concentration on platform’s revenues.