Research

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Published / Accepted Papers

In recent years, European regulators have debated restricting the time an online tracker can track a user to protect consumer privacy better. Despite the significance of these debates, there has been a noticeable absence of any comprehensive cost-benefit analysis. This article fills this gap on the cost side by suggesting an approach to estimate the economic consequences of lifetime restrictions on cookies for publishers. The empirical study on cookies of 54,127 users who received ~128 million ad impressions over ~2.5 years yields an average cookie lifetime of 279 days, with an average value of €2.52 per cookie. Only ~13% of all cookies increase their daily value over time, but their average value is about four times larger than the average value of all cookies. Restricting cookies’ lifetime to one year (two years) decreases their lifetime value by ~25% (~19%), which represents a decrease in the value of all cookies of ~9% (~5%). In light of the €10.60 billion cookie-based display ad revenue in Europe, such restrictions would endanger €904 million (€576 million) annually, equivalent to €2.08 (€1.33) per EU internet user. The article discusses these results' marketing strategy challenges and opportunities for advertisers and publishers.


Ad blockers allow users to browse websites without viewing ads. Online news publishers that rely on advertising income tend to perceive users’ adoption of ad blockers purely as a threat to revenue. Yet, this perception ignores the possibility that avoiding ads —which users presumably dislike—may affect users’ online news consumption behavior in positive ways. Using 3.1 million visits from 79,856 registered users on a news website, this research finds that ad blocker adoption has robust positive effects on the quantity and variety of articles users consume. Specifically, ad blocker adoption increases the number of articles that users read by 21.0%–43.2%, and it increases the number of content categories that users consume by 13.4%–29.1%. These effects are stronger for less-experienced users of the website. The increase in news consumption stems from increases in repeat visits to the news website, rather than in the number of page impressions per visit. These postadoption visits tend to start from direct navigation to the news website, rather than from referral sources. The authors discuss how news publishers could benefit from these f indings, including exploring revenue models that consider users’ desire to avoid ads.


Knowledge of consumers' willingness to pay (WTP) is a prerequisite to profitable price-setting. To gauge consumers' WTP, practitioners often rely on a direct single question approach in which consumers are asked to explicitly state their WTP for a product. Despite its popularity among practitioners, this approach has been found to suffer from hypothetical bias. In this paper, we propose a rigorous method that improves the accuracy of the direct single question approach. Specifically, we systematically assess the hypothetical biases associated with the direct single question approach and explore ways to de-bias it. Our results show that by using the de-biasing procedures we propose, we can generate a de-biased direct single question approach that is accurate enough to be useful for managerial decision-making. We validate this approach with two studies in this paper. 


Getting the price right is essential for successful new product introductions. An accurate estimate of consumers' willingness to pay is a crucial part of this task. Measurement of willingness to pay for innovations, however, often yields biased results. In this paper, we investigate consumer-related characteristics and motives that might underlie this bias. Drawing on the elaboration likelihood model, we develop a conceptual model to identify consumer characteristics relevant for preference measurement for innovative products. In doing so, two main factors that potentially influence hypothetical bias are distinguished: ability and motivation. Our conceptual discussion and empirical results demonstrate that the validity of willingness to pay statements is higher among consumers who show a high ability to assess the new product's utility and who are truly interested in purchasing the new product. Counter to intuition, willingness to pay statements from innovators, consumers with good product category knowledge, or consumers who perceive the new product to be highly innovative are relatively more biased and should be interpreted with caution. This research is among the first to look at consumer characteristics rather than methodological issues when it comes to measuring consumer willingness to pay for innovative products. Our conceptual discussion and empirical examination of the drivers of hypothetical bias can be used to refine the validity of the results of the direct willingness to pay approach. These findings should help improve new product pricing surveys and open new avenues for research in measuring consumer preferences.


This study compares the performance of four commonly used approaches to measure consumers’ willingness to pay with real purchase data (REAL): the open-ended (OE) question format; choice-based conjoint (CBC) analysis; Becker, DeGroot, and Marschak's (BDM) incentive-compatible mechanism; and incentive-aligned choice-based conjoint (ICBC) analysis. With this five-in-one approach, the authors test the relative strengths of the four measurement methods, using REAL as the benchmark, on the basis of statistical criteria and decision-relevant metrics. The results indicate that the BDM and ICBC approaches can pass statistical and decision-oriented tests. The authors find that respondents are more price sensitive in incentive-aligned settings than in non-incentive-aligned settings and the REAL setting. Furthermore, they find a large number of “none” choices under ICBC than under hypothetical conjoint analysis. This study uncovers an intriguing possibility: Even when the OE format and CBC analysis generate hypothetical bias, they may still lead to the right demand curves and right pricing decisions. 

Working Papers 

Using a randomized eld experiment with a leading European newspaper, we study both the inertia anticipated by consumers and the actual inertia they experience. Our experiment among two million readers varies promotional subscription terms, including whether or not the contract automatically renews to a full-price subscription by default. By analyzing their subscription behavior over two years, we study how consumers respond to inertia-inducing subscription contracts in the short- and long-run. We find strong inertia. Half of the auto-renewal contract takers continue to a full-price subscription while rarely using it. At the same time, consumers preempt their future inertia; 24%-36% of potential subscribers avoid subscribing when offered an auto-renewal promo. Further, offering an auto-renewal contract decreases the share of subscribers over the two years after the promo by 10%. Even though auto-renewal generates higher revenue in the medium-run due to payments from inert subscribers, auto-renewal and auto-cancel are revenue equivalent after one year, but with fewer subscribers in auto-renewal. Using a mixed-types model, we estimate that while 70% of consumers are inert, a large majority of them (at least 58%) are aware of their inertia. Our results highlight the importance of sophistication about future biases in the market; sophisticated consumers avoid exploitation and are missed by researchers and firms analyzing only takers, since takers are selected on their naivete.


Regulators and browsers increasingly restrict user tracking to protect users’ privacy online. Such restrictions also have economic implications for publishers that rely on selling advertising space to finance their business, including their content. According to an analysis of 42 million ad impressions related to 111 publishers, when user tracking is unavailable, the raw price paid to publishers for ad impressions decreases by about -60%. After controlling for differences in users, advertisers, and publishers, this decrease remains substantial, at -18%. More than 90% of the publishers realize lower prices when prevented from engaging in user tracking. Publishers offering broad content, such as news websites, suffer more from user tracking restrictions than publishers with thematically focused content. Collecting a user’s browsing history, perceived as generally intrusive to most users, generates negligible value for publishers. These results affirm the prediction that ensuring user privacy online has substantial costs for online publishers; this article offers suggestions to reduce these costs.


This study examines whether the GDPR achieved its aim of increasing users’ online privacy by decreasing the extent to which users’ activity is tracked online. The analysis uses a difference-in-differences design with a balanced panel of 717 websites—distinguishing between websites that were subject to the GDPR and websites that were not (control group). Data obtained from WhoTracks.me identify the trackers encountered on each website by millions of users in the EU and the US during the 1 month before and 20 months after the enactment of the GDPR. Findings show that, across all websites, the quantity of online tracking (measured as the number of trackers per website) increased over time; however, this increase was less pronounced among websites subject to the GDPR (an increase from 12 to 19 trackers versus 12 to 21 trackers in the control group). Subsequent analysis suggests that these effects may be attributable to the extent to which fines were imposed on noncompliant websites. Together, the results suggest that enacting the GDPR increased users’ online privacy to a small extent but that users are still tracked to a substantial degree. 


Policymakers worldwide draft privacy laws that require trading-off between safeguarding consumer privacy and preventing economic loss to companies that use consumer data. However, little empirical knowledge exists as to how privacy laws affect companies’ performance. Accordingly, this paper empirically quantifies the effects of the enforcement of the EU’s General Data Protection Regulation (GDPR) on online user behavior over time, analyzing data from 6,286 websites spanning 24 industries during the 10 months before and 18 months after the GDPR’s enforcement in 2018. A panel differences estimator, with a synthetic control group approach, isolates the short- and long-term effects of the GDPR on user behavior. The results show that, on average, the GDPR’s effects on user quantity and usage intensity are negative; e.g., the number of total visits to a website decrease by 4.9% and 10% due to GDPR in respectively the short- and long-term. These effects could translate into average revenue losses of $7 million for e-commerce websites and almost $2.5 million for ad-based websites 18 months after GDPR. The GDPR’s effects vary across websites, with some industries even benefiting from it; moreover, more-popular websites suffer less, suggesting that the GDPR increased market concentration. 

Selected Work-in-Progress 

Invited Talks and Conference Presentations

Ad-hoc Reviewer

Marketing Science, Information Systems Research, International Journal of Research in Marketing, Israel Science Foundation, German Science Foundation.