🧵1/ Our first meta-science paper (with 350+ coauthors) is published today in Nature. It presents one of the largest-ever reproducibility projects in economics & political science.
Here’s what we found 👇
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Extended abstracts are due February 28th, to present in beautiful Bergamo, Italy @beriapaolo.bsky.social @jonathanhall.bsky.social
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Join us at the International Transportation Economics Association Annual Conference & School at the University of Bergamo, Italy, June 15-19, 2026! Submit your transportation economics research by Feb 28. Two paper prizes available!
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P.S. Those in literature may like our summaries of the 56 papers we found. 12/12
🔗Find the full paper at jhall.github.io/documents/Va... 11/12
Takeaway #2: Average effects are small. General statements about the impact of ride-hailing on transit ridership, traffic congestion, and traffic fatalities should reflect that the average estimate is close to zero and not statistically significant. 10/12
Takeaway #1: Context matters. Dense NY or London ≠ mid‑sized Vancouver. But for many US/Canadian metros, long‑run ride‑hailing impacts on transit & congestion are likely modest. 9/12
Publication bias? Surprisingly little. 8/12
📚🔍To put these results in context, we then conducted a meta-analysis. We screened 2,597 papers, kept 56. Across modes & countries, lots of heterogeneity, but average estimates hover near zero; ~⅓ of papers find no significant effect (but boosts🚊and depresses 🚍). 7/12
⚠️Traffic fatalities: noisy data give wide CI [‑30%, +199%]. We can’t rule much in or out. 6/12
🚗Traffic congestion: point estimates slightly ↑ but never statistically significant; CI [‑6.1%, +20.7%]. No evidence that “Uber makes gridlock explode” 5/12
We use a weighted average of US/CA cities to build a synthetic Vancouver that has Uber to estimate how ride-hailing impacts transit ridership, traffic congestion, and traffic fatalities. What do we find? 3/12
In 2012 B.C.’s regulator blocked Uber, labeling it a “$75‑minimum limo.” For 7 years Vancouver was a big North‑American city with no ride‑hailing—an economist’s natural experiment. 2/12
🚨New paper!🚨In “VancUber: The Long‑Run Effect of Ride‑hailing on Public Transportation, Congestion, and Traffic Fatalities” (forthcoming @ CJE), Craig Palsson, John Cairncross, and I use Vancouver’s ban on Uber/Lyft until 2020 to ask “what if ride‑hailing never came?” 1/12
🚨 FINAL REMINDER: Submit your abstract for ITEA 2025 by Feb 28! Join top transportation economists at Northwestern this June for the conference (June 25-27) and annual school (June 23-25). Keynote by MIT's Dave Donaldson. Student discounts available! transportation.northwestern.edu/news-events/...
New research alert! Our study investigates the effectiveness of human-only, AI-assisted, and AI-led teams in assessing the reproducibility of quantitative social science research. We've got some surprising findings!
Join us at the International Transportation Economics Association Annual Conference & School at Northwestern University, June 23-27, 2025! Featuring keynote speaker Prof. Dave Donaldson (MIT). Submit your transportation economics research by Feb 28. Two paper prizes available!
🚨 New paper! 🚨
Should Cities Tax Uber and Lyft?
Thread below, and link to the WP here:
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