NBER Working Papers by Chris Nosko

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Working Papers

January 2015The Limits of Reputation in Platform Markets: An Empirical Analysis and Field Experiment
with Steven Tadelis: w20830
We argue that reputation mechanisms used by platform markets suffer from two problems. First, buyers may draw conclusions about the quality of the platform from single transactions, causing a reputational externality across sellers. Second, for a variety of reasons we discuss, reputations will be biased. We document these problems using eBay data and claim that platforms can benefit from identifying and promoting higher quality sellers. We create an unobservable measure of seller quality and demonstrate the benefits of our approach through a controlled experiment that prioritizes better quality sellers. We highlight the importance of reputational externalities and chart an agenda that aims to create more realistic models of platform markets.
May 2014Consumer Heterogeneity and Paid Search Effectiveness: A Large Scale Field Experiment
with Tom Blake, Steven Tadelis: w20171
Internet advertising has been the fastest growing advertising channel in recent years with paid search ads comprising the bulk of this revenue. We present results from a series of large scale field experiments done at eBay that were designed to measure the causal effectiveness of paid search ads. Because search clicks and purchase behavior are correlated, we show that returns from paid search are a fraction of conventional non-experimental estimates. As an extreme case, we show that brand-keyword ads have no measurable short-term benefits. For non-brand keywords we find that new and infrequent users are positively influenced by ads but that more frequent users whose purchasing behavior is not influenced by ads account for most of the advertising expenses, resulting in average returns that ...

Published: Thomas Blake & Chris Nosko & Steven Tadelis, 2015. "Consumer Heterogeneity and Paid Search Effectiveness: A Largeā€Scale Field Experiment," Econometrica, Econometric Society, vol. 83, pages 155-174, 01. citation courtesy of

October 2010Supply Responses to Digital Distribution: Recorded Music and Live Performances
with Julie Holland Mortimer, Alan Sorensen: w16507
Changes in technologies for reproducing and redistributing digital goods (e.g., music, movies, software, books) have dramatically affected profitability of these goods, and raised concerns for future development of socially valuable digital products. However, broader illegitimate distribution of digital goods may have offsetting demand implications for legitimate sales of complementary non-digital products. We examine the negative impact of file-sharing on recorded music sales and offsetting implications for live concert performances. We find that file-sharing reduces album sales but increases live performance revenues for small artists, perhaps through increased awareness. The impact on live performance revenues for large, well-known artists is negligible.

Published: Mortimer, Julie Holland & Nosko, Chris & Sorensen, Alan, 2012. "Supply responses to digital distribution: Recorded music and live performances," Information Economics and Policy, Elsevier, vol. 24(1), pages 3-14. citation courtesy of

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