La science économique au service de la société

Colloque | Platforms and the sharing economy | 5 juillet

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Paris School of Economics a le plaisir de vous inviter au colloque « Platforms and the sharing economy » organisé par la Chaire Soutenabilité de la mobilité longue distance.

  • Date : Mercredi 5 juillet 2023, 8:30-12:30
  • Lieu : Paris School of Economics
    48 boulevard Jourdan, 75014 Paris, salle R2-21



8:30-9:15 : Welcome coffee

9:15-10:00 : « Cycling Towards Cleaner Cities ? Evidence from New York City’s Bike Share Program », Vincent Thorne (Trinity College Dublin)
Discussant : Lucas Perez (PSE)
What is the impact of cycling infrastructure on air quality in cities ? This paper leverages the staggered rollout of New York City’s bike share program to estimate the effect of cycling infrastructure on air pollution concentrations. I combine the universe of bike share trips with ground-level, high-resolution observational air pollution measures between 2010 and 2019. Through a routing algorithm, I use the location of bike share stations to map areas where road traffic is expected to decrease after the introduction of bike share. I compare these areas with others where traffic was likely unaffected using a staggered difference-in-differences strategy to retrieve causal estimates. I find that the deployment of bike share is associated with a 3% reduction in black carbon and 13% reduction in nitric oxide concentrations, both pollutants associated with road traffic. Back-of-the-envelope valuation of the health and mortality benefits associated with the reduction in nitric oxide concentrations suggests that bike share prevented up to $327 million in social damages. In addition, I investigate potential mechanisms and show that the introduction of bike share is associated with a decrease in short taxi trips in areas served by bike share, which I interpret as suggestive evidence that bike share substitutes road traffic.

10:00-10:45 : « The Price of Trust, Women’s Participation and Ethnic Sorting in p2p Markets. Evidence from BlaBlaCar », Ignacio Berasategui (Cemfi)
Discussant : Elena Stancanelli (PSE and CNRS)
Sorting based on observable features such as gender or race has a widespread negative perception. Peer-to-peer markets, fostered by the boom of online applications, are no exception to this trend. Policymakers around the globe are urging platforms to reduce the information that users share through their profile pictures and names, as a way to prevent discrimination. Given the role that observable features play building users’ trust, these measures may hinder their participation in asymmetric fashion, affecting especially specific population segments. To analyze the implications of profile information on female participation and ethnic sorting, I focus on BlaBlaCar, the world ́s leading car-sharing platform for non-professional drivers and passengers. I construct a novel data set that contains detailed information of all the users on both market sides and all transactions in the routes that connect eight of the largest cities in France, between October 2020 and March 2021. Using a structural framework that accommodates the main strategic decisions of both market sides, this paper shows that women prefer to travel with other women and that there exists a substantial degree of ethnic-based homophily. This paper also provides evidence that alternative designs limiting the sorting abilities of users do not necessarily benefit ethnic minorities and that women from the ethnic majority tend to be the population segment whose participation and welfare reduces the most when anonymous marketplaces are imposed

10:45-11:00 : Coffee break

11:00-11:45 : « Choice, Welfare, and Market Design : An Empirical Investigation of Feeding America’s Choice System », Sam Altmann (University of Oxford)
Discussant : Manpreet Singh (PSE)
Feeding America, an organisation responsible for feeding 130,000 Americans every day, distributes donated food among a network of participating food banks. Feeding America’s allocation mechanism, the ‘Choice System’, uses first-price auctions to allow food banks to signal which types of food they need from Feeding America. This provides food banks a large degree of choice over the types of food they receive. This paper examines the welfare and distributional consequences of enabling this choice. I apply a dynamic auction model to Choice System bidding data, estimating the distribution of food banks’ heterogeneous and time-varying needs. I then use these estimates to compare the Choice System to the previous allocation mechanism employed by Feeding America which gave food banks very limited choice. I estimate that the Choice System increased welfare by the equivalent of a 17.1% increase in the quantity of food being allocated.

11:45-12:30 : « Satiation, unraveling and capping prices. Designing peer-to-peer platforms with internal currencies », Julius Goedde (PSE)
Discussant : Nikhil Vellodi (PSE)
I examine how to design peer-to-peer sharing platforms that use internal currencies instead of real money. Individuals and policymakers are reluctant to use real money in a variety of contexts and are increasingly experimenting with token-money. The design of these systems often mimics real markets, with the key difference that individuals must earn tokens by supplying on the platform and can only spent them by consuming on the same platform. Examples include trading goods and services among local residents, food among food banks and organ donors among hospitals. As individuals typically only have a limited demand for the specific goods on the platform, some may become satiated and reduce their supply. This might induce others to reduce their supply in turn and lead to unraveling – an equilibrium with inefficiently low trade. I illustrate with a stylized overlapping generations model that reducing the price of attractive goods may increase trade volume and aggregate welfare. In the empirical part, I focus on a popular platform for exchanging holiday homes. Using proprietary data on the universe of transactions I present a range of stylized facts consistent with satiation and unraveling. My preliminary results suggest that compressed prices may indeed improve upon unrestricted prices despite possible side-effects like misallocation. A broader insight is that lessons from traditional markets may not easily extend to markets without real money.

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Cet évènement est organisé par la Chaire Soutenabilité de la mobilité longue distance. La chaire a pour ambition de porter un projet de recherche sur les mobilités terrestres de demain afin de les rendre décarbonnées et connectées. Elle est centrée sur l’étude de plateformes de « mobility as a service » (MaaS) proposant à leurs utilisateurs des trajets qui s’appuient sur des moyens de transport bas carbone (covoiturage, bus et train). Les recherches menées relèveront principalement de l’économie industrielle, mais mobiliseront également d’autres champs disciplinaires (e.g. économie de l’environnement et économie comportementale).