Ad allocation with secondary metrics

Motivated by Online Ad allocation with advertisers that pursue multiple objectives, we introduce and study a problem of Ad Allocation with Secondary Metrics. For instance, advertisers pay per click which is the primary metric the platforms optimize for, but require the average cost of a conversion - the secondary metric - to be below some threshold. This is an explicit option for Facebook advertisers. Further, even when this is not an explicit option and the advertisers can only configure pay per click campaigns, sales teams often negotiate with advertisers in terms of expected conversion thresholds and this becomes the implicit secondary metric for the ad platform or the sales teams. We study this problem under both market and advertiser perspectives. ; (Market Perspective) We adopt the per-impression auctioning approach used in the industry and propose modified sorting and allocation rules for the auction that explicitly take into account the secondary metric performance. We run the algorithm in an industrial setting on live traffic in a large ad network
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. We find a significant impact on the realized secondary metrics without compromising primary metrics. For instance, the linear scoring function gives 30% lift on secondary metric and was selected as a default allocation algorithm in the ad network. ; (Advertiser Perspective) We present an efficient dynamic programming algorithm that calculates the best response strategy for each advertiser. We implement and test this solution on offline impression data and compute strategies for advertisers. We find that for a fraction of advertisers, we could not find non empty allocation. We cross check this result with the online results, and find that 92% of these ads did not meet their target conversions. This suggests that these ads may have unrealistic expectations.