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This paper analyzes the impact of intermediary concentration on the allocation of revenue in online platforms. We study sponsored search documenting how advertisers increasingly bid through a handful of specialized intermediaries. This enhances automated bidding and data pooling, but lessens competition whenever the intermediary represents competing advertisers. Using data on nearly 40 million Google keyword auctions, we first apply machine learning algorithms to cluster keywords into thematic groups serving as relevant markets. Using an instrumental variable strategy, we estimate a decline in the platform’s revenue of approximately 11 percent due to the average rise in concentration associated with intermediary merger and acquisition activity.

This paper contributes to the analysis of quantitative indicators (i.e., red flags or screens ) to detect corruption in public procurement. It presents an approach to evaluate corruption risk in public tenders through standardized ML tools applied to detailed data on the content of calls for tenders. The method is applied to roadwork contracts in Italy and three main contributions are reported. First, the study expands the set of commonly discussed indicators in the literature to new ones derived from operative practices of police forces and the judiciary. Second, using novel and unique data on firm-level corruption risk, this study validates the effectiveness of the indicators. Third, it quantifies the increased corruption-prediction ability when indicators that are known to be unavailable to the corruption-monitoring authority are included in the prediction exercise. Regarding the specific red flags, we find a systematic association between high corruption risk and the use of multi-parameter awarding criteria. Furthermore, predictability of the red flag makes them ineffective as prediction tools: the most obvious and scrutinized red flags are either uncorrelated with corruption or, even, negatively associated with it, as it is the case for invoking special procedures due to “urgency,” or the extent of publicity of the call for tender.

We study entry and bidding in procurement auctions where contracts are awarded to the bid closest to a trimmed average bid. These auctions, common in public procurement, create incentives to coordinate bids to manipulate the bid distribution. We present statistical tests to detect coordinated entry and bidding choices. The tests perform well in a validation dataset where a court case makes coordination observable. We use the tests to detect coordination in a larger dataset where it is suspected, but not known. The results are used to interpret a major market shakeout following a switch to first price auctions.

This paper presents evidence on the perverse trade-off that first price auctions induce between low prices at the awarding stage and poor ex post performance when bids are not binding commitments. By exploiting the different timing with which first price auctions were introduced in Italy to procure public works, this study finds that at least half of the cost savings from lower winning prices are lost because of ex post renegotiation. Screening the lowest price bid for its responsiveness prevents performance worsening but also reduces the initial cost savings by a third and induces delays in awarding the contract.

This article contrasts two auction formats often used in public procurement: first price auctions with ex post screening of bid responsiveness and average bid auctions (ABAs), in which the bidder closest to the average bid wins. The equilibrium analysis reveals that their ranking is ambiguous in terms of revenues, but the ABA is typically less efficient. Using a data set of Italian public procurement auctions run alternately under the two formats, a structural model of bidding is estimated for the subsample of first price auctions and used to quantify the efficiency loss under counterfactual ABAs.

This paper shows how in Medicare Part D insurers' gaming of the subsidy paid to low-income enrollees distorts premiums and raises the program cost. Using plan-level data from the first five years of the program, I find multiple instances of pricing strategy distortions for the largest insurers. Instrumental variable estimates indicate that the changes in a concentration index measuring the manipulability of the subsidy can explain a large share of the premium growth observed between 2006 and 2011. Removing this distortion could reduce the cost of the program without worsening consumer welfare.

We empirically study how the interplay between entry and subcontracting choices is affected by the use of different auction formats in public procurement. The difference-in-differences strategy used exploits a data set of auctions for public works run alternately under first price and average bid auctions. We find that the use of first price auctions causes a marked decline in both entry and subcontracting. We also find that the type of firms entering first price auctions changes with firms becoming more likely to bid jointly with other firms in ad hoc joint ventures. Data, as supplemental material, are available at http://dx.doi.org/10.1287/mnsc.2014.2071 . This paper was accepted by Teck-Hua Ho, behavioral economics .

The transition of the advertising market from traditional media to the internet has induced a proliferation of marketing agencies specialized in bidding in the auctions that are used to sell ad space on the web. We analyze how collusive bidding can emerge from bid delegation to a common marketing agency and how this can undermine the revenues and allocative efficiency of both the generalized second-price auction (GSP, used by Google, Microsoft Bing, and Yahoo!) and the Vickrey–Clarke–Groves (VCG) mechanism (used by Facebook). We find that despite its well-known susceptibility to collusion, the VCG mechanism outperforms the GSP auction in terms of both revenues and efficiency. This paper was accepted by Gabriel Weintraub, revenue management and market analytics .

La publicidad online ha experimentado un rápido crecimiento a lo largo de las dos últimas décadas, superando hoy día su valor total al de la publicidad tradicional en los medios en EE.UU. Entre los múltiples factores que subyacen a esta tendencia, la capacidad de los mecanismos de subasta para tasar eficazmente lo que valoran los anunciantes ha desempeñado un papel clave en la configuración del comportamiento de los motores de búsqueda y los medios sociales más prominentes. El presente ensayo examina la evolución de los principales mecanismos de subasta de ventas publicitarias online, ilustra cómo los cambios producidos pueden interpretarse a la luz de la teoría económica, y utiliza esas mismas herramientas para examinar algunos avances potenciales en la evolución de las subastas de publicidad online.

Public procurement accounts for around 12% of global GDP and 63% of expenditures are managed by subnational governments across OECD countries. In Italy, municipalities can impose penalties on contractors for breaches of contract, for example delays in delivery, often leading to contractors suing the municipality in local courts, which can in turn further delay delivery. As such the efficiency of the local judiciary can have a strong bearing on the final delivery of public works. This study assesses the causal effect of those efficiencies on the ultimate delay in the execution of local public contracts. The results show that inefficient courts lead to further delays in the execution of public works that are already long overdue. However, inefficient courts also appear to deter companies to pursue litigation in cases where delays were much lower. Overall, the impact on long-overdue contracts prevails and the aggregate effect is negative: the total delay in the execution of local public contracts in the 25% least efficient courts is more than twice as large as in the 25% most efficient courts.