Séminaire d’équipe Pedro Chahuara le jeudi 18 mai à 14h

Online Mining of Web Publisher RTB Auctions for Revenue Optimization
In the online adversiment market there are two main actors: the publishers that offer a space for advertisement in their websites and the announcers who compite in an auction to show their advertisements in the available spaces. When a user accesses an internet site an auction starts for each ad space, the profile of the user is given to the announcers and they offer a bid to show an ad to that user. The publisher fixes a reserve price, the minimum value they accept to sell the space.
In this talk I will introduce a general setting for this ad market and I will present an engine to optimize the publisher revenue from second-price auctions, which are widely used to sell on-line ad spaces in a mechanism called real-time bidding. The engine is fed with a stream of auctions in a time-varying environment (non-stationary bid distributions, new items to sell, etc.) and it predicts in real time the optimal reserve price for each auction. This problem is crucial for web publishers, because setting an appropriate reserve price on each auction can increase significantly their revenue.
I consider here a realistic setting where the only available information consists of a user identifier and an ad placement identifier. Once the auction has taken place, we can observe censored outcomes : if the auction has been won (i.e the reserve price is smaller than the first bid), we observe the first bid and the closing price of the auction, otherwise we do not observe any bid value.
The proposed approach combines two key components: (i) a non-parametric regression model of auction revenue based on dynamic, time-weighted matrix factorization which implicitly builds adaptive users’ and placements’ profiles; (ii) a non-parametric model to estimate the revenue under censorship based on an on-line extension of the Aalen’s Additive Model.