About

Nils Wernerfelt is an Assistant Professor of Marketing at the Kellogg School of Management, having joined the faculty in 2023. His core research focuses on policy questions facing the digital advertising industry, with broader interests in online marketing, analytics, and digital platforms. His recent work includes analyses of the effects of privacy regulation on ad effectiveness and market structure, estimates of the consumer value of ad personalization, and large-scale meta-analyses of digital advertising effectiveness. Professor Wernerfelt holds a PhD in Economics from MIT and a BA in Mathematics from Harvard. Prior to joining Kellogg, he was a Director on the Economics and Policy Research team at Meta.

Research topics

• Political Science
• Sociology
• Psychology
• Social psychology
• Demography
• Economics
• Demographic economics
• Social Science
• Economic growth

Selected publications

• Experiment Registration for The Consumer Welfare Effects of Online Ads: Evidence from a 9-Year Experiment

  AEA Randomized Controlled Trials · 2025-06-02

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• The Consumer Welfare Effects of Online Ads: Evidence from a Nine-Year Experiment

  American Economic Review Insights · 2025-11-25

  articleSenior author

  Research on the effects of online advertising on consumer welfare is limited due to challenges in running large-scale field experiments. We analyze a long-running field experiment on Facebook in which a random subset of users received no ads in their newsfeeds. Using an incentive-compatible deactivation experiment, we find no significant differences in users’ valuation of Facebook across a representative sample of 53,083 Facebook users in the ads and no ads groups. Our sample size allows for precise estimates, suggesting that either the disutility of ads is relatively small or that there are offsetting benefits, such as product discovery. (JEL C93, D12, D44, L82, M37)

  PublisherDOI

• Experiment Registration for The Consumer Welfare Effects of Online Ads: Evidence from a 9-Year Experiment

  AEA Randomized Controlled Trials · 2025-06-02

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  PublisherDOI

• Estimating the Value of Offsite Tracking Data to Advertisers: Evidence from Meta

  Marketing Science · 2024-09-30 · 13 citations

  article1st authorCorresponding

  We run a large-scale field experiment at Meta to estimate how valuable offsite tracking data are for digital ad effectiveness.

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• The Consumer Welfare Effects of Online Ads: Evidence from a 9-Year Experiment

  SSRN Electronic Journal · 2024-01-01

  articleOpen accessSenior author
  PublisherDOI

• Estimating the Value of Offsite Tracking Data to Advertisers: Evidence from Meta

  SSRN Electronic Journal · 2024-01-01 · 1 citations

  articleOpen access1st authorCorresponding
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• Digital Advertising and Market Structure: Implications for Privacy Regulation 

  SSRN Electronic Journal · 2024-01-01

  preprintOpen accessSenior author
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• Digital Advertising and Market Structure: Implications for Privacy Regulation

  SSRN Electronic Journal · 2024-01-01 · 3 citations

  articleOpen accessSenior author
  PublisherDOI

• The Consumer Welfare Effects of Online Ads: Evidence from a 9-Year Experiment

  National Bureau of Economic Research · 2024-08-01 · 4 citations

  reportOpen accessSenior author

  Research on the causal effects of online advertising on consumer welfare is limited due to challenges in running large-scale field experiments and tracking effects over extended periods.We analyze a long-running field experiment of online advertising in which a random 0.5% subset of all users are assigned to a group that does not ever see ever ads.We recruit a representative sample of Facebook users in the ads and no-ads groups and estimate their welfare gains from using Facebook using a series of incentive-compatible choice experiments.We find no significant differences in welfare gains from Facebook.Our estimates are relatively precisely estimated reflecting our large sample size (53,166 participants).Specifically, the minimum detectable difference in median valuations at standard thresholds is $3.18/month compared to a baseline valuation of $31.95/month for giving up access to Facebook.That is, we can reject the hypothesis that the median disutility from advertising exceeds 10% of the median baseline valuation.Our findings suggest that either the disutility of ads for consumers is relatively small, or that there are offsetting benefits, such as helping consumers find products and services of interest.

  PublisherDOI

• Estimating the Value of Offsite Tracking Data to Advertisers: Evidence from Meta

  National Bureau of Economic Research · 2024-08-01 · 8 citations

  reportOpen access1st authorCorresponding

  Third-party cookies and related ‘offsite’ tracking technologies are frequently used to share user data across applications in support of ad delivery. These data are viewed as highly valuable for online advertisers, but their usage faces increasing headwinds. In this paper, we quantify the benefit to advertisers from using such offsite tracking data in their ad delivery. With this goal in mind, we conduct a large-scale, randomized experiment that includes more than 70, 000 advertisers on Facebook and Instagram. We first estimate advertising effectiveness at baseline across our broad sample. We then estimate the change in effectiveness of the same campaigns were advertisers to lose the ability to optimize ad delivery with offsite data. In each of these cases, we use recently developed deconvolution techniques to flexibly estimate the underlying distribution of effects. We find a median cost per incremental customer at baseline of $38.16 that under the median loss in effectiveness would rise to $49.93, a 31% increase. Further, we find ads targeted using offsite data generate more long-term customers per dollar than those without, and losing offsite data disproportionately hurts small scale advertisers. Taken together, our results suggest that offsite data bring large benefits to a wide range of advertisers.

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Frequent coauthors

• Johannes Stroebel

  21 shared

• Daniel Deisenroth

  19 shared

• Utsav Manjeer

  14 shared

• Richard Zeckhauser

  Harvard University Press

  13 shared

• Theresa Kuchler

  13 shared

• Christopher Hooton

  George Washington University

  13 shared

• Anna Dreber

  Stockholm School of Economics

  12 shared

• Steven Tadelis

  University of California, Berkeley

  12 shared

Awards & honors

• Faculty Teaching Awards