Noel Johnson

Economist at GMU. Very mid practitioner of Brazilian jiu jitsu. I like dogs.

[Noel Johnson @noeldjohnson]

🧵 1/ The most famous party trick in AI: take word vectors and compute "king − man + woman." You (often) get queen — evidence the model learned gender as a direction in space.

Could you pull that off using nothing but the titles of books printed in Europe,
1450–1650?

[Noel Johnson @noeldjohnson]

Here's the working paper. Comments welcome: https://t.co/Zjpsb6GXUR

[Noel Johnson @noeldjohnson]

🧵1/ Before refrigeration, the smallpox vaccine was a live virus with no shelf life. So how did the British move it across 19th-century India? They chained it through the arms of children. Vaccinate one, wait a week, harvest the lymph from the blister, use it on the next.

[Noel Johnson @noeldjohnson]

7/ In our research, districts closest to those 1857 reprisals vaccinated less for decades. The vaccine worked, and smallpox was merciless. But a life-saving technology can still fail when it arrives by force, from a state you have every reason to distrust. Working paper 👇/end

[Joachim Voth @joachim_voth]

Spatial errors are a potential problem in applied economics. If u use cross-sectional data, but neighboring observations are really similar, you overstate the confidence you can have in your results. The problem is not new. Recently, some new methods have allowed us to tackle

[Eric Smith @Eric_Smith08]

Amazon Prime costs $139/year.

Most members use 2 features: free shipping and Prime Video.

That's a $139 subscription doing the job of a $5.99 delivery fee.

J.P. Morgan estimates the actual value of Prime benefits at approximately $1,430/year more
than 10x the membership cost. But most of that value sits unclaimed behind tabs, menus,
and pages 200 million members have never opened.

And 4 of those benefits expire monthly. If you don't claim them by the end of the month,
they're gone. Amazon resets the clock. You paid for them. You lost them.

Amazon is counting on you not knowing.

Here are the 12 Prime benefits most members have never activated including the 4 that
vanish every 30 days 🧵

[QJE @QJEHarvard]

#QJE Aug 2026, #11, “Praying for Rain,” by Espín-Sánchez (@JosespinSanchez), Gil-Guirado and Ryan: https://t.co/NQ5pYrehPr

[Noel Johnson @noeldjohnson]

Staring at my Claude dashboard, waiting for my monthly spend to go up, indicating that my batch job is being processed. Modern research.

[Mark Koyama @MarkKoyama]

Adam Smith: Historical Political Economist https://t.co/E7T6hLDYFW (in honor of the 250th of the WoN)

[Noel Johnson @noeldjohnson]

RT @ATabarrok: Land reclamation from the ancient Iraqi city of Ur to Alexander the Great’s siege of Tyre, the amazing flood tanks built und…

[Noel Johnson @noeldjohnson]

The down side is I’ve been administering oral exams for a few semesters and have noted my enrollments are declining. This makes my usual classes at risk of being cancelled by the admin. I doubt they’ll adjust their policies quickly.

[Noel Johnson @noeldjohnson]

Assigning essays that students work on outside of class has been meaningless for at least a year now. The future is in-class exams or oral exams online.

[Brendan Nyhan (@BrendanNyhan on 🟦☁️) @BrendanNyhan]

Friends don't let friends continue to give exams and papers that are not adapted to the current AI landscape (this is AFTER 27 bailed so the reality is even worse)

PS Props to students 1, 22, and 31

[Noel Johnson @noeldjohnson]

It is, once again, leaf blower season. As tradition dictates, a haiku…

Blowers hum and wail,
Thoughts drift like leaves in the gust—
Workday blown away.

[Noel Johnson @noeldjohnson]

@Francis57614181 2/ And Spain's interesting. About 16% of its established presses passed to a widow, right alongside France (17%) and the Netherlands (16.5%), above Germany (13.5%). Italy 1%, Portugal 0% were the low cases. Spain's lower overall share is fewer/smaller presses, not weaker rights.

[Noel Johnson @noeldjohnson]

🧵1/ In some Renaissance cities women printed as many as 1 in 5 of all books. In Italy, almost none. Here's the map, and it traces one of the deepest divides in European history.

[Noel Johnson @noeldjohnson]

@Francis57614181 1/ Fair catch. "Iberia" was sloppy of me. Spain (~2%) isn't near zero, it sits above several northern countries, exactly as you say. The clean low cases are Italy and Portugal. I shouldn't have lumped Spain in.

[Alice Evans @_alice_evans]

Europe was extremely patriarchal:

Men not only dominated every institution of power, but also controlled the means of large-scale ideological persuasion.

100% of all books reviewed below were authored by men.

Men ran 95-100% of all printing presses in the cities shown.

[Data from @noeldjohnson, just flipped the labels].