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Katja Seim Publications

Publish Date
International Journal of Industrial Organization
Abstract

The role of demand curvature in determining firm behavior in symmetric oligopolistic product markets is well-understood. We consider the empirically relevant discrete choice differentiated product demand and point to two forces that drive curvature in logit demand: the impact of outside-good spending on the consumer’s indirect utility and the heterogeneity in this response across consumers. We use the canonical example of the ready-to-eat cereal market (Nevo, 2000) to contrast elasticity and curvature estimates across several workhorse models. We illustrate that the log-concave Multinomial Logit and Nested Logit demands yield significantly biased curvature estimates. In contrast, a Mixed Logit specification generates a wider range of curvatures, including curvatures larger than one. These results are of immediate relevance to the robust assessment of tax incidence and the pass-through of cost savings, such as from a horizontal merger, in differentiated product markets.

Econometrica
Abstract

We quantify the distortionary effects of nexus tax laws on Amazon’s distribution net- work investments between 1999 and 2018. We highlight the role of two features of the expansion of Amazon’s network: densification of the network of distribution facilities and vertical integration into package sortation. Densification results in a reduction in the cost of shipping orders, but comes at the expense of higher facility operating costs in more expensive areas and lower scale economies of processing shipments. Nexus laws furthermore generate additional sales tax liabilities as the network grows. Combining data on household spending across online and offline retailers with detailed data on Amazon’s distribution network, we quantify these trade-offs through a static model of demand and a dynamic model of investment. Our results suggest that Amazon’s expansion led to significant shipping cost savings and facilitated the realization of aggregate economies of scale. We find that abolishing nexus tax laws in favor of a non-discriminatory tax policy would induce the company to decentralize its network, lowering its shipping costs. Non-discriminatory taxation would also entail lower revenue, however, as tax-inclusive prices would rise, resulting in a fall in profit overall. This drop and the decline in consumer welfare from higher taxes together fall short of the increases in tax revenue and rival profit, suggesting that the abolishment of nexus laws would lead to an increase in total welfare.

Abstract

This is the fifth in a series of papers prepared by a collection of economists and policy experts in the United States, the UK, and the European Union who have studied, and are committed to the improvement of, competition in digital markets. Previous papers addressed consumer protection in online markets, regulating the market for general search services, the concepts of “fairness” and “contestability” as used in the Digital Markets Act, and the use of “equitable interoperability” as a “super tool” to restore and encourage competition in online markets.

Discussion Paper
Abstract

This paper is concerned with competition in digital platform markets where network effects are strong. As is widely acknowledged, these markets have an inherent tendency towards concentration, leaving consumers with little competition in the market. We explain how interoperability regulation can help stimulate competition in the market in a way that benefits consumers.

Discussion Paper
Abstract

We analyze the use of the concepts of fairness and contestability in the Digital Markets Act (DMA) and propose formal definitions rooted in the economic analysis of digital markets as well as the goals of the proposed law. We discuss the implication of these concepts for innovation in digital markets.

Discussion Paper
Abstract

Consumer protection law is vital for ensuring that market-based economies work in the economic interest of consumers as well as businesses, and thus to the benefit of civil society. This is the case for online markets just as it is for offline markets. However, despite broad consensus on these points, too little has been done to ensure that the various standards applicable in offline markets are sufficient or adequate to guarantee efficiency and fairness in online markets. This paper outlines eleven key features of online markets that might necessitate standards additional to or different from those that are applicable offline, and provides a menu of possible policies in relation to each. Many of these are general to all online markets, but some are specific to the largest digital platfoms. Many if not most of our policy proposals could be enacted through minor changes to existing law or regulation or through decisional law interpreting existing legislation. Some have already been implemented in some jurisdictions. What is needed in all jurisdictions, however, is a regulator or regulators with sufficient expertise around technical issues such as A/B testing and algorithmic decision-making to understand, anticipate, and remedy the myriad ways that online firms can disadvantage consumers.

Discussion Paper
Abstract

This paper identifies a set of possible regulations that could be used both to make the search market more competitive and simultaneously ameliorate the harms flowing from Google’s current monopoly position. The purpose of this paper is to identify conceptual problems and solutions based on sound economic principles and to begin a discussion from which robust and specific policy recommendations can be drafted.

Discussion Paper
Abstract

This is the sixth in a series of papers prepared by a collection of economists and policy experts in the United States, the UK, and the European Union who have studied, and are committed to the improvement of, competition in digital markets. Previous papers addressed consumer protection in online markets, regulating the market for general search services, the concepts of “fairness” and “contestability” as used in the Digital Markets Act, the use of “equitable interoperability” as a “super tool” to restore and encourage competition in online markets, and coherence between US and European approaches to digital regulation.

Discussion Paper
Abstract

We quantify the distortionary effects of nexus tax laws on Amazon’s distribution network investments between 1999 and 2018. We highlight the role of two features of the expansion of Amazon’s network: densification of the network of distribution facilities and vertical integration into package sortation. Densification results in a reduction in the cost of shipping orders, but comes at the expense of higher facility operating costs in more expensive areas and lower scale economies of processing shipments. Nexus laws furthermore generate additional sales tax liabilities as the network grows. Combining data on household spending across online and offline retailers with detailed data on Amazon’s distribution network, we quantify these trade-offs through a static model of demand and a dynamic model of investment. Our results suggest that Amazon’s expansion led to significant shipping cost savings and facilitated the realization of aggregate economies of scale. We find that abolishing nexus tax laws in favor of a non-discriminatory tax policy would induce the company to decentralize its network, lowering its shipping costs. Non-discriminatory taxation would also entail lower revenue, however, as tax-inclusive prices would rise, resulting in a fall in profit overall. This drop and the decline in consumer welfare from higher taxes together fall short of the increases in tax revenue and rival profit, suggesting that the abolishment of nexus laws would lead to an increase in total welfare.