iiinova — where your digital self keeps evolving

Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 28/09/2026

Wecome France! Dashboard already looks so much nicer with this addition. Thanks @abergeaud.bsky.social for pointing out the data availability. Others: Keep sending indices or data suggestions. I am just the methods nerd, dont know much about data...

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 27/09/2026

Who hasn’t wished for consistent European micro-geographic house-price indices? Start: Germany + England & Wales in one dashboard. Data ready to download. Send me yours sites.google.com/view/ahlfeld... Send me your AHS index from your country! @bsoeberlin.bsky.social @heblich.bsky.social

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CRC Rationality & Competition @rationalitycrc.bsky.social · 21/09/2026

Why more business districts don't equal stronger urban centers: Our new global analysis demonstrates that as the number of commercial hubs within a city increases, their collective share of total employment actually falls.

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Where the Services Are: Mapping the Ultra-Dense Core of the Modern City

Ahlfeldt, Albers & Behrens: “Prime Locations” Insights 2026, 8(3)

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 13/09/2026

Switch among population, employment, wages, rents, output and land values—or compare open-city, closed-city and fixed-distribution cases. Try it: qsetransport.ahlfeldt.com Built on the ARSW model (Econometrica) and AAB-PL data (AER: Insights). @bsoeberlin.bsky.social

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 13/09/2026

Click “Run counterfactual” and QUETRANSPORT solves the spatial equilibrium. This illustrative closed-city run converged across 246 London cells in 0.55 seconds, mapping population effects and reporting welfare, output, land rent and commuting results.

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 13/09/2026

Draw the intervention itself. Here I sketch a stylised west–east Crossrail corridor and add six stations. You can also upload a baseline network or draw polygons that change productivity, amenities, or housing supply.

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 13/09/2026

Start with London—or choose from 125 global cities and hundreds of US metropolitan areas. Set the grid, travel speeds, and spillovers. No installation is needed: the Python model runs in the browser.

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 13/09/2026

Spatial-equilibrium modelling now works directly in your browser. Choose a city, draw a policy on the map, and see results by grid cell in near real time. Here is a stylised Crossrail experiment in London. 🧵 sites.google.com/view/ahlfeld...

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 28/08/2026

How common is polycentricity? 88.1% of small US metros have one prime location. Among large metros: 11.1% monocentric, 16.7% duocentric, 72.2% polycentric. Next question: what determines urban spatial structure? Spoiler: the timing of transport matters. @bsoeberlin.bsky.social

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 28/08/2026

Some striking numbers: • Midtown Manhattan: 1.71m jobs on 11 km² (~156k/km²) • Chicago’s Loop: 801k jobs • Lower Manhattan: 432k jobs (~110k/km²) Table: the extraordinary concentration of activity in prime locations.

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 28/08/2026

We identify 33 prime locations across 56 US metropolitan areas and another 286 across 125 global cities. A few tiny places can concentrate up to half of tradable-services jobs. Figure: employment density and detected prime locations in Chicago, Los Angeles and New York.

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 28/08/2026

Lesson learned: Don’t write a book and pretend it is a paper. :-) The first chapter of our “book of prime locations” is now published in AER: Insights. What is a prime location—and what does it reveal about urban spatial structure? 🧵 www.aeaweb.org/articles?id=...

aeaweb.org

Prime Locations

(September 2026) - We develop a method for delineating prime locations—ultradense clusters of economic activity—within cities and apply it to comprehensive establishment data covering all US metropoli...

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 25/08/2026

Run GE counterfactuals for 100s of cities in minutes. Download an analysis-ready city grid from AABPL toolkit. Describe a transport change. Run. QUETRANSPORT produces maps, statistics and diagnostics. AABPL: github.com/Ahlfeldt/AAB... Showcase: github.com/Ahlfeldt/QSE... @bsoeberlin.bsky.social

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 18/08/2026

2/2 Gábor’s concern: good IVs are hard to find. So for Topic 25 I created a synthetic world with the AB2022 toolkit. We generate cities from known primitives, giving us relevant, excludable IVs by design. github.com/Ahlfeldt/AB2... @bsoeberlin.bsky.social

github.com

GitHub - Ahlfeldt/AB2022-toolkit: The economics of skyscrapers: A synthesis toolkit

The economics of skyscrapers: A synthesis toolkit. Contribute to Ahlfeldt/AB2022-toolkit development by creating an account on GitHub.

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 18/08/2026

1/2 New Applied Econometrics lecture slides are online: github.com/Ahlfeldt/Lec... Topics 13–24 follow Békés & Kézdi’s excellent, applied and case-based textbook. I highly recommend it. Thanks @gaborbekes.bsky.social for sharing slides, data & code.

github.com

GitHub - Ahlfeldt/Lectures-AppliedEconometrics: Humboldt University Applied Econometrics lecture slides

Humboldt University Applied Econometrics lecture slides - Ahlfeldt/Lectures-AppliedEconometrics

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 01/08/2026

We find economic gains (productivity, commuting, affordability) and costs (disamenities from congestion and crowding). On average, gains dominate at the margin. But to make informed statements for individual cities, we'd need more data to relax functional form assumptions and allow for heterogeneity

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 31/07/2026

Thrilled our paper was accepted at @reveconstudies.bsky.social! Fond of our indirect-inference estimate of density disamenity—learning from macro, matching reduced-form causal moments in structural models @bsoeberlin.bsky.social github.com/Ahlfeldt/DPs/blob/main/GA_NBS_JR_-_SkyscraperRevolution.pdf

Title page and abstract of “The Skyscraper Revolution: Global Economic Development and Land Savings” by Gabriel M. Ahlfeldt, Nathaniel Baum-Snow, and Remi Jedwab. The abstract reports that removing height constraints raises welfare in developing economies, tall buildings foster urban growth and compactness, and indirect inference yields a density-disamenity elasticity of −0.11.

Figure A8, “Model Simulated Height Elasticities by Density Disamenity.” The graph plots population, built area, rent, and wage height elasticities against the density elasticity of amenities. Model curves match the reduced-form population and area moments near a density-disamenity elasticity of −0.11.

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 18/07/2026

Yesterday (today for some of us 😀), the @bsoeberlin.bsky.social QSE ended on a high. Thanks so much to all the speakers, long-term visitors, short-term guests, and the regulars at the seminars (and socials). What a fantastic community! sites.google.com/view/bqse/bq...

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 30/06/2026

Thanks to #BritishEmbassyBerlin for an excellent conference to honour the #KensingtonTreaty One lesson from the regional policy panel: create spatially balanced agglomeration. Updated my slides on growth & spatial inequality based on what I learned github.com/Ahlfeldt/pre... @bsoeberlin.bsky.social

github.com

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 10/06/2026

At this scale, we only have list prices/rents for Germany. The paper contains a small section on listed vs transaction prices in Berlin. They track each other rather closely over the given time period. But I would not surprised if list prices lagged entering a downturn. github.com/Ahlfeldt/DPs...

github.com

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 09/06/2026

For the underlying methodology: www.sciencedirect.com/science/arti... All data available here: github.com/Ahlfeldt/AHS...

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 09/06/2026

Great dashboard implementation our methodology from @cep-lse.bsky.social @bsoeberlin.bsky.social research to illustrate microgeographic property prices and rents in Germany by @tagesspiegel.de. Try clicking on your postcode. 😀 interaktiv.tagesspiegel.de/lab/der-inte...

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Georg Weizsäcker @georgweizsaecker.bsky.social · 10/04/2026

Our urban economics colleagues at @humboldtuni.bsky.social are amazingly productive. (And therefore, according to their latest research 👇🏼 we can expect our office rents to rise.) @heblich.bsky.social, @ahlfeldt.bsky.social

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 24/03/2026

@tagesspiegel.de with coverage of the AHSY index (w dashboard): interaktiv.tagesspiegel.de/lab/gewerbem... Here is our @bsoeberlin.bsky.social paper with the underlying methodology: github.com/Ahlfeldt/DPs... For those who cant get enough: our 1h live debate 😎: www.tagesspiegel.de/kneipe-weg-k...

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 19/03/2026

We revised our Skyscraper Revolution paper github.com/Ahlfeldt/DPs... Added indirect inference to estimate the QoL effect of density by matching causal reduced-form estimates in the model => more realistic counterfactuals. Quick read @voxeu.org: cepr.org/voxeu/column... @bsoeberlin.bsky.social

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CRC Rationality & Competition @rationalitycrc.bsky.social · 16/03/2026

Why is there less beautiful architecture than we'd like? Our research shows that because neighbours get the benefits for free while builders pay extra, the market systematically undersupplies the architecture we prefer, making a construction subsidy the most efficient fix.

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Why Market Forces Alone Undersupply Distinctive Architecture

Ahlfeldt, Pietrostefani & Zhang: "The Economics of Architecture" CRC Discussion Paper No. 561

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Berlin School of Economics @bsoeberlin.bsky.social · 19/02/2026

🏙️ Do big cities boost productivity more than we think? A study shows the benefits of urban density are reflected not only in higher wages, but also in higher commercial rents. Ignoring rent effects may underestimate the true economic gains of large cities. berlinschoolofeconomics.de/about-us/new...

The Price of Productivity
by Gabriel M. Ahlfeldt, Stephan Heblich, Tobias Seidel, and Fan Yin

Focus and Research Question

The study asks whether the productivity advantages of cities – known as agglomeration effects – are reflected not only in higher wages but also in higher commercial rents. It examines whether focusing on wages alone understates the true economic benefits of large cities.

Data and Measurement

The researchers build a new commercial rent index for Germany using five million property listings from 2007 to 2024. They measure rents at a fine geographic level and identify central business districts (CBDs) as areas with unusually high economic density.

Methodological Approach

They estimate how commercial rents decline with distance from the CBD and how CBD rents increase with city size. To identify causal effects, they use historical population as an instrument for current city size.

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Berlin School of Economics @bsoeberlin.bsky.social · 18/02/2026

📺 On @rbb24.de, @ahlfeldt.bsky.social discussed the entry of low-price coffee chains. ☕ He argued market-wide price declines are unlikely, as cafés compete beyond price. Current pricing may not be sustainable, though part of productivity gains reaches consumers. 👉 www.rbb-online.de/abendschau/v...

rbb-online.de

Chinesische Kaffeekette startet mit Dumpingpreisen

Billig, schnell, per App: Mit "Cotti Coffee" startet eine chinesische Kaffeekette in Berlin. Der erste Standort an der Friedrichstraße setzt auf Niedrigpreise und hohe Frequenz. Die Branche fragt sich...

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 17/02/2026

☕Kaffee für alle oder schicke Cafés für coole Kieze? 🤎 Wir diskutieren live zur prime time in der @rbb24.de Abendschau @humboldtuni.bsky.social @bsoeberlin.bsky.social Interview: box.hu-berlin.de/f/3b351d1660... Ganzer Ganzer Beitrag: www.rbb-online.de/abendschau/v...

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 15/02/2026

"The price of productivity is not paid in wages alone. A large share is paid in rents." Our @bsoeberlin.bsky.social INSIGHTS piece summarizes why considering commercial rent capitalization is important to properly estimating agglomeration effects. berlinschoolofeconomics.de/insight/the-...

berlinschoolofeconomics.de

The Price of Productivity

by Gabriel Ahlfeldt (HU Berlin, LSE), Stephan Heblich (University of Toronto), Tobias Seidel (University of Duisburg-Essen), Fan Yin (HU Berlin)

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 12/02/2026

And thanks a ton to our friends at the FDZ at @rwi.bsky.social @phibre.bsky.social for making available the raw data - what a service to the spatial economics in Germany!

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 12/02/2026

And here it is, the first micro-geographic commercial rent index for Germany in its full beauty. Maps of top-12 German cities in the online supplement of the paper... @heblich.bsky.social

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 12/02/2026

The agglomeration elasticity may be larger than widely believed (if we account for capitalization in commercial floor space prices). And the first micro-geographic commercial rent index for Germany!!! 😎 @bsoeberlin.bsky.social DP: opus4.kobv.de/opus4-hsog/f... Data: github.com/Ahlfeldt/AHS...

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Berlin School of Economics @bsoeberlin.bsky.social · 29/01/2026

🏙️ Is “good #architecture” just aesthetics – or real #economic value? 👥 A new #paper by @ahlfeldt.bsky.social, E. Pietrostefani, and A. Zhang shows how distinctive design can raise prices not only for one building, but also for its neighbourhood. 📑 berlinschoolofeconomics.de/about-us/new...

How Architecture Creates Economic Value Beyond Buildings

by Gabriel M. Ahlfeldt, Elisabetta Pietrostefani, and Ailin Zhang

Focus and Research Question

The paper asks how much “good architecture” is worth economically, and whether markets deliver too little of it. The key issue is that design benefits can extend beyond the building itself.

Why markets may underprovide design

High-quality design can create spillovers — benefits to neighbors and the wider area that the developer cannot fully charge for. This can lead to less investment in design than is socially desirable.

Evidence base and data

The authors synthesise evidence from many empirical studies linking architectural design to property prices and rents. They distinguish between effects on the designed building itself and effects on nearby buildings.

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Berlin School of Economics @bsoeberlin.bsky.social · 21/01/2026

🏙️ The #Economics of #Architecture @ahlfeldt.bsky.social, Elisabetta Pietrostefani & Ailin Zhang bring architectural quality into urban & welfare economics, documenting spillovers, heterogeneous preferences & a coordination problem in design investment. 👇 berlinschoolofeconomics.de/insight/the-...

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 12/01/2026

Good architecture is a posterchild public good: non-rival and non-excludable. Had great fun using the economics toolbox to study why developments look rather underwhelming and simulate what policies could lead to more beautiful cities. @bsoeberlin.bsky.social github.com/Ahlfeldt/DPs...

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 05/12/2025

Assessed values are good for quantification of QSMs. List prices better for hedonic valuation using panel identification. Evidence and replication studies from the NL and NYC in our @cep-lse.bsky.social DP! cep.lse.ac.uk/_NEW/PUBLICA...

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 26/11/2025

Ever wondered what housing value proxy for sales prices to use? Long story (in our @cesifo.org DP) short: Assessed values are good for quantification of QSMs. List prices better for hedonic valuation using panel identification. www.ifo.de/en/cesifo/pu... @hans-koster.bsky.social

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CRC Rationality & Competition @rationalitycrc.bsky.social · 16/11/2025

How can traditional models fall short in measuring urban appeal? Our analysis reveals that neglecting mobility frictions causes an underestimation of the urban quality-of-life premium (QoL): increasing a region's population is associated with a significant increase in QoL. 190researchblog.subs...

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WIFO @wifo.bsky.social · 10/09/2025

#WIFO Research Seminar with @ahlfeldt.bsky.social (@humboldtuni.bsky.social) – The Geography of Life: Evidence from Copenhagen This seminar will take place on 24 September 2025 at 12:40 pm. Register now: veranstaltungen@wifo.ac.at ▶️ Join us buff.ly/K1fQU4A

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Christian Traxler @chtraxler.bsky.social · 21/07/2025

.@hertieschool.bsky.social & IfW Kiel are jointly 🚨 recruiting a Professor of International Economics🚨 (Associate/Full). 👉 apply.interfolio.com/169770 Great opportunity to join Berlin's thriving econ community. No kings here. Deadline: Sep 30, 2025 Please share widely! #EconSky

apply.interfolio.com

Apply - Interfolio {{$ctrl.$state.data.pageTitle}} - Apply - Interfolio

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 07/08/2025

I am too young to get nostalgic (at least I pretend), but 10 years after the "Berlin Wall" paper and with 15 years newer data I realize two things: 1) The Berlin spatial structure did not change that much 2) how much more convenient it has gotten to collect land values 😀 @reddingecon.bsky.social

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 27/07/2025

UPDATE: more impression from the epic www.bqse.de boat event: sites.google.com/view/bqse/bq... Thanks to @humboldtuni.bsky.social Innovation #HumboldtInnovation for facilitating!

bqse.de

www.bqse.de

Photocredit: wirestock

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 21/07/2025

What a fabulous 2025 @bsoeberlin.bsky.social www.bqse.de seminar season it has been! Thanks to all the co-organizers, our manager @immanuelfeld.bsky.social , all speakers, guests, and locals! You have been a fantastic spatial community! sites.google.com/view/bqse/bq...

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Gabriel M Ahlfeldt @ahlfeldt.bsky.social · 17/07/2025

Last day of the @bsoeberlin.bsky.social course in Quantitative Spatial Economics. What a great cohort! If you spot any of these faces on the job market, don't hesitate! Thoroughly impressed by their coursework—the nerdy discussions during the lectures: priceless! 🫰 sites.google.com/view/bqse/bq... f

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