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John Fallon @john-fallon-econ.com · 26/12/2025

Something about highly experienced teachers seems to help more. Maybe accumulated tacit knowledge transfers through close interaction? Effects peak around 15-20 years of partner experience, then decline slightly.

Graph showing difference-in-differences estimates by partner experience bins from 0-5 years through 20+ years. The bars show near-zero effects for less experienced partners, peaking at approximately 0.05-0.06 standard deviations for partners with 15-20 years experience, then declining slightly.

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John Fallon @john-fallon-econ.com · 26/12/2025

But here's the problem: Schools most commonly pair two inexperienced teachers together. Only highly experienced partners (16+ years) produce lasting benefits. Organizations are missing opportunities to accelerate skill development through strategic pairing.

Heatmap showing pairing frequency by experience levels of both teachers. Yellow indicates most frequent pairings, blue indicates less common. The brightest yellow cell shows inexperienced teachers (0-5 years) paired together most frequently, with cooler blue tones for pairings involving more experienced teachers.

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John Fallon @john-fallon-econ.com · 26/12/2025

Do pairs improve at working together over time? Without controls, longer duration predicts better outcomes. With teacher fixed effects, this reverses—better teachers stay together; pairs don't improve through practice. May even be a cost to not managing a class alone.

Graph showing two series of coefficients plotting student test scores against years as a pair. Blue line without teacher experience controls shows slight upward trend. Red line with teacher experience controls shows flat or slightly negative relationship, indicating pairs don't improve together over time and may have opportunity costs.

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John Fallon @john-fallon-econ.com · 26/12/2025

We know teachers improve with experience (Papay & @matthewakraft.com 2015), but how? And can we accelerate it? Strategic collaboration might be one answer—pairing with experienced colleagues could compress years of learning-by-doing into shorter periods.

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John Fallon @john-fallon-econ.com · 26/12/2025

Main result: Teachers paired with highly experienced special ed colleagues (16+ years) improve by 0.10 standard deviations—and this persists after returning to solo teaching. Partners with 0-7 or 8-15 years show no lasting benefit. The experience level matters.

Event study graph with three panels showing effects by special education partner experience level (0-7, 8-15, and 16+ years). Only the 16+ years panel shows clear positive effects after co-teaching, reaching approximately 0.10 standard deviations improvement.

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John Fallon @john-fallon-econ.com · 26/12/2025

Advantage: I track general education teachers before pairing with a special ed teacher, during collaboration, and after returning to solo teaching. This lets me separate temporary help from genuine skill transfer. Most pairs break up after a year, so I observe many returning to solo classrooms.

Graph showing probability of co-teaching pair separation by years together. Starting above 60% after one year, the separation rate gradually declines to approximately 40% by year five, indicating most pairs break up quickly.

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John Fallon @john-fallon-econ.com · 26/12/2025

The setting: Co-teaching pairs one general education teacher with one special education teacher in the same classroom (to comply with inclusion mandates). Assignment driven by special ed enrollment & scheduling. Since it happens early in careers, quality is less well known—good for identification!

Graph showing hazard rates for entering co-teaching by years of experience. Two lines compare special education teachers (higher rate, peaking around 25% for novices) versus general education teachers (lower rate, around 10% for novices), both declining sharply with experience.

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John Fallon @john-fallon-econ.com · 26/12/2025

🚨🚨🚨New working paper! 🚨🚨🚨 "Learning by Doing (Together): Collaboration and Teacher Skill Formation" Do workers genuinely learn from collaboration, or just benefit while working together? I study teacher partnerships to find out. Paper: john-fallon-econ.com Presenting at #ASSA2026 #EconSky 1/10

Event study graph showing student test score differences before and after teachers first co-teach. The line shows parallel pre-trends near zero, then jumps to approximately 0.04 standard deviations above zero in years following co-teaching, with confidence intervals shown blue bars.

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John Fallon @john-fallon-econ.com · 24/11/2025

This matters beyond just doctors and chiropractors. Think: Nurse practitioners vs doctors Psychologists vs LICSWs Any profession where substitutes have separate boards Competitive licensing changes everything about how we evaluate regulation. Full Paper: john-fallon-econ.com/Files/JMP.pdf (9/9)

Geographic maps of practitioner distribution

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John Fallon @john-fallon-econ.com · 24/11/2025

The model estimates reveal that boards act like profit-maximizing cartels (Stackelberg equilibrium), not benevolent regulators. This is regulatory capture in action - boards prioritize incumbent profits over public welfare. (8/9)

Charts showing policies under different decision mechanisms and the associated theoretical welfare

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John Fallon @john-fallon-econ.com · 24/11/2025

So why would raising YOUR barriers help when competitors enter? I build a structural model showing boards want to engage in "cream-skimming" - they want to set standards just high enough to poach high-ability workers from rival professions. (7/9)

Theoretical best response graph for chiropractor boards

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John Fallon @john-fallon-econ.com · 24/11/2025

The tricky part: does licensing cause these changes, or do areas with more chiropractors just adopt licensing? I use an IV strategy with non-bordering counties (F-stats 338-699) and find chiropractors actually INCREASED 2-12 per 100k despite now facing barriers. (6/9)

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John Fallon @john-fallon-econ.com · 24/11/2025

But there's a cost: doctors per capita fell by 17-40 per 100k people. This is huge - it explains much of what historians attribute to the famous Flexner Report. Maybe those "quality reforms" were actually strategic responses to competitive threats. (5/9)

Event study showing a decline in MD prevalence after the adoption of a chiropractic board

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John Fallon @john-fallon-econ.com · 24/11/2025

Here's what's striking: BOTH professions benefited economically. Doctors saw 26% higher home values and chiropractors saw 44% higher home values. Licensing didn't just restrict entry - it legitimized chiropractors while doctors raised their own barriers. (4/9)

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John Fallon @john-fallon-econ.com · 24/11/2025

I digitized AMA records from 1907-1960 and found medical boards systematically tightened requirements after states licensed chiropractors: Required internships shot up 10-15pp Pass rates fell 5pp College requirements rose ~10pp (3/9)

Event study showing internship requirement increases

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John Fallon @john-fallon-econ.com · 24/11/2025

We usually think of occupational licensing as professions policing themselves. But what happens when competing professions each have their own licensing boards? Turns out they weaponize regulations against each other. (2/9)

1921 chiropractor ad claiming to treat influenza

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John Fallon @john-fallon-econ.com · 24/11/2025

I'm John Fallon, a labor economist on the job market. My JMP uncovers something wild: when chiropractors got licensed in the early 1900s, medical boards responded by making it HARDER to become a doctor. Why would competition lead to stricter regulations? 🧵 john-fallon-econ.com (1/9)

Line graph showing cumulative state adoption of chiropractic boards over time

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John Fallon @john-fallon-econ.com · 14/03/2025

The resulting change in teacher composition had surprisingly persistent effects! @wheelockpolicybu.bsky.social

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John Fallon @john-fallon-econ.com · 14/03/2025

Just saw a great paper by @michaelbriskin.bsky.social ! He shows that WWII led to a massive teacher shortage that led to lower wages and lower educational attainment for affected students #AEFP2025 #Econsky

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