Barnes City Volatility Coefficient

What is your
city's sigma?

A unified model that estimates how city conditions shape what classrooms can produce. Type any U.S. city.

Calculating Barnes Volatility Coefficient
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Barnes Volatility Coefficient  ·  σ
Sigma Score  ·  Scale 0–10
Stressor Variables
Attenuation & Structure
What This Means for Classrooms
What This Sigma Means for Your Teachers
Illustrative profiles. Not real individuals. Calculated from typical inputs at this sigma level.
Experienced Teacher
Ms. Reyes
Year 8  ·  Trust Capital: 8/10  · 
--
Growth Index
--
Trust Capital
8
Adaptive Resp.
9
Decay Rate
26%
First-Year Teacher
Mr. Davis
Year 1  ·  Trust Capital: 3/10  · 
--
Growth Index
--
Trust Capital
3
Adaptive Resp.
7
Decay Rate
46%
The Gap
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What Is Sigma

The number the system
never calculated.

Every child carries something to school. Violence exposure. Housing instability. Economic exclusion. Food insecurity. Infrastructure deficit. These conditions do not stay at the door. They enter the classroom, suppress what students can absorb, and consume what teachers build. The Barnes Volatility Coefficient puts a formal number on that burden for the first time.

σ
Barnes Volatility Coefficient  ·  Scale 0–10
A single formally specified score derived from five weighted stressor domains, compounded when they fire simultaneously, and adjusted for community buffering capacity and policy coherence. The result estimates what city conditions impact classrooms before a teacher says a word.
Low
0 – 2
Conditions not the primary obstacle
Moderate
2 – 4.5
Investment produces clear return
Elevated
4.5 – 6.5
Cross-sector action required
Acute
6.5+
Sustained systemic investment
Five Stressor Domains
V
Violence
Violent crime rate, shooting incidents, community safety. Violence influences cognitive availability in classrooms through acute and chronic stress responses.
H
Housing Instability
Eviction rates, rent burden, displacement. The most direct predictor of school mobility and educational disruption.
Ep
Economic Exclusion
Prime-age labor force non-participation, neighborhood unemployment. Determines household stability and ambient stress.
F
Food Insecurity
Food access gaps, FRL concentration. Directly tied to cognitive function and classroom readiness.
I
Infrastructure Deficit
Environmental burden, transit gaps, aging facilities. Present in every high-sigma city, compounds the other four.
"
Brilliance is not rare. The instruments that measure it just were not built for the rooms where most of it lives.
Tyree Barnes  ·  Founder
The System

From city conditions
to classroom outcomes.

Start with the conditions. Understand what teachers are working against. Then coach with precision. CitySigma connects city-level environmental data to classroom-level development — three instruments, one coherent system for supporting teachers more effectively.

01
Barnes City Volatility Equation
City Sigma Score
Five stressor domains scored from publicly available data, weighted by their relationship to educational outcomes, compounded when they fire simultaneously, and adjusted for community buffering capacity. The output estimates what city-level conditions have shaped in classroom terms. A mayor's housing siting choice now has an estimated instructional impact — expressed in the sigma score of every school in that catchment area.
Any U.S. city Ward-level precision Policy decision mapping
02
Barnes Instructional Equation
Classroom Growth Index
Sigma enters the instructional equation as the volatility ceiling — constraining student receptivity and comprehension transfer in proportion to its severity. The Growth Index estimates what a teacher generates given those specific conditions. Not what the rubric expects. What the conditions allow. The same teacher with identical skill scores dramatically differently in a sigma-7 school than in a sigma-2 school. The equation makes that visible for the first time. Use the simulator to see it.
Trust capital Volatility ceiling Condition-adjusted output
Growth Index Simulator
Drag sigma to see what conditions cost a strong teacher.
City Sigma
5.5
Growth Index
--
out of 10.0 possible
Stressor Pass-Through
--
reaches classrooms unmitigated
Drag the slider to see how sigma changes what this teacher can produce.
03
Coherence Coaching
Condition-Adjusted Development
With a Growth Index in place, coaching becomes more precise. Rather than comparing a teacher to a universal standard, you compare her to what is achievable given the specific conditions of her school. The gap between what the model estimates and what she produces is where targeted development lives. The goal is not rubric compliance. It is documented growth in context.
Condition-adjusted targets Formally documented growth Equity-rooted coaching
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Coherence Institute

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Free online courses for teachers, coaches, and school leaders. Learn to read sigma, calculate Growth Index, and build a coaching practice grounded in what conditions actually allow — not what rubrics assume.

Course 01
Understanding City Sigma and What It Means for Your School
For teachers, coaches, and administrators
Learn how the Barnes City Volatility Coefficient is constructed, how to read a sigma score for your city or ward, and what the five stressor domains mean in the daily life of a school. This course reframes what you have always known as a formally specified reality.
Free Self-paced 4 modules Enrolling Now
Course 02
The Growth Index: A New Model for Instructional Coaching
For instructional coaches and principals
Learn the Barnes Instructional Equation in depth. Understand how sigma enters the Growth Index as a volatility ceiling, how to set condition-adjusted development targets for teachers, and how to document growth against a formally specified baseline. The coaching model that was always missing.
Free Self-paced 6 modules Coming Summer 2026
Who This Is For

Anyone who has known
the measurement was wrong.

Built for everyone who has spent a career inside a system that measured teachers and students without a single variable for the conditions they were navigating every day.

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Mayors and Policy Teams
See what your decisions cost classrooms.
Housing siting, violence prevention investment, and economic development choices now have a formally specified cost in classroom terms. The sigma score connects your policy decisions to instructional outcomes across every ward in your city.
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🏫
Superintendents and District Leaders
Stop deploying the same intervention everywhere.
Schools with radically different sigma conditions require radically different investment strategies. The instrument tells you what each school is working against before a single professional development dollar is spent.
Learn the system
📋
Principals and Instructional Coaches
Give your teachers what they deserve.
Performance must be understood in context — not evaluated without it. The Growth Index accounts for the specific conditions teachers are working against, making development targets accurate rather than arbitrary.
Enroll in Course 01
🔬
Researchers and Policy Analysts
A formally specified bridge that has not existed.
A formally specified behavioral model grounded in 29 peer-reviewed citations. Five directional hypotheses pre-registered before data collection. The first formal instrument connecting urban policy research to classroom outcomes through a single shared variable.
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Coherence Coach

Coaching tools built
for the conditions teachers face.

Start with a single session. Scale to a full platform. Engage us for district-level analysis and custom implementation.

Single Session
Coherence Coach v.1
One observation. One condition-adjusted coaching brief. The entry point to the full system.
$47
one-time · per session
$37 after completing Course 01
What's included
City sigma auto-pull for any U.S. city
Teacher profile inputs
Five-variable observation scoring with descriptor bands
Barnes Growth Index calculation
Condition-adjusted coaching brief
Named development priority for this session
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Platform License
Coherence Coach v.2
Persistent teacher profiles, trajectory tracking, and session-to-session comparison. The full coaching platform.
Individual
$197
per year
or
School Building
$697
per year · up to 12 users
$157 / $557 after completing Course 01
Everything in v.1, plus
Persistent teacher profiles across sessions
Growth Index trajectory charts
Session-to-session score comparison
Pre-filled sliders from previous session
Trajectory-aware coaching briefs
Dashboard with school-level overview
Multi-teacher management
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District & Policy
Coherence Audit
Custom ward or district-level sigma analysis, sigma-adjusted outcome report, and coaching roadmap delivered by our team.
$3,500
per engagement · school or ward level
What's delivered
Full ward or school-level sigma analysis
Sigma-adjusted outcome report against state data
Gap attribution — conditions vs. instruction
Coaching roadmap for each school profile
Policy brief ready for superintendent or mayor
District-wide pricing available on request
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Course 01 discount applies at checkout with your completion certificate  ·  All prices in USD  ·  School building license covers up to 12 named users
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Ready to see what sigma means for your city, district, or school?
The sigma score is the starting point. The Coherence Audit is the full diagnostic. If you are a mayor, superintendent, or policy team ready to connect your decisions to your outcomes formally, reach out.
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For mayors, superintendents, and policy teams. A 30-minute session with the instrument, your city's data, and the full system explained.
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Full ward-level sigma analysis cross-referenced against your district's outcome data. The formal diagnostic your reform decisions need.
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Free Courses
For teachers, coaches, and principals. Learn the system. Change what coaching means in your building.
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The instrument is built. The data is public. The sigma score is free. The work of formally measuring what these communities carry starts now.

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