Department of Economics
270 Bay State Road
Boston, MA 02215
NBER Program Affiliations:
NBER Affiliation: Faculty Research Fellow
NBER Working Papers and Publications
|October 2017||Marketing Agencies and Collusive Bidding in Online Ad Auctions|
with Maris Goldmanis, Antonio Penta: w23962
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 and Microsoft-Bing and Yahoo!) and the of VCG mechanism (used by Facebook). We find that, despite its well-known susceptibility to collusion, the VCG mechanism outperforms the GSP auction both in terms of revenues and efficiency.
|December 2016||Insurers' Response to Selection Risk: Evidence from Medicare Enrollment Reforms|
with Andrea Guglielmo: w22876
Evidence on insurers’ behavior in environments with both risk selection and market power is largely missing. We fill this gap by providing one of the first empirical accounts of how insurers adjust plan features when faced with potential changes in selection. Our strategy exploits a 2012 reform allowing Medicare enrollees to switch to 5-star contracts at anytime. This policy increased enrollment into 5-star contracts, but without risk selection worsening. Our findings show that this is due to 5-star plans lowering both premiums and generosity, thus becoming more appealing for most beneficiaries, but less so for those in worse health conditions.
|November 2016||Past Performance and Procurement Outcomes|
with Giancarlo Spagnolo, Riccardo Pacini: w22814
Reputational incentives may be a powerful mechanism for improving supplier performance. We analyze their role in contract awarding, exploiting an experiment run by a firm which introduced a new vendor rating system scoring suppliers' past performance and linking it to the award of future contracts. We study responses in both price and performance to the announcement of the switch from price-only to price-and-rating auctions. Across the 136 parameters scored, overall compliance improves from 25 percent to 80 percent. Improvements involve all parameters and suppliers, but are more pronounced for parameters receiving a higher weight in the announced scoring auction. Prices do not significantly change overall, but we find some evidence of lower prices right after the announcement when supplier...
|June 2015||The Welfare Effects of Supply-Side Regulations in Medicare Part D|
with Maria Polyakova, Stephen P. Ryan: w21298
The efficiency of publicly-subsidized, privately-provisioned social insurance programs depends on the interaction between insurer behavior and public subsidies. We study this interaction within Medicare Part D Prescription Drug Plan (PDP) markets. Using a structural model of supply and demand, we find: consumers purchase too few and too socially-costly PDP plans; insurers price near marginal cost; the primary driver of welfare is the opportunity cost of government spending on other Medicare programs; and the current subsidization policy achieves a level of total welfare close to that obtained under an optimal in-kind subsidy, but is far from the social planner's first-best solution.