Part I
Why systems surprise us
- 034 demonstrations
Events Are Not Explanations
A reference mode is a behavior target, and the shapes it names depend on a few parameters.
- 044 demonstrations
The Bathtub Most People Misread
A level and a rate have different units, and reading one off the other is the error.
- 054 demonstrations
The Beer Game and the Cost of Local Rationality
Four sensible ordering desks, joined by delays, make a swing no desk intended.
Part II
From a messy problem to a dynamic hypothesis
- 084 demonstrations
Causal-Loop Diagrams Without Causal Theater
A diagram is a list of claims, and each claim can be counted, audited and removed.
- 094 demonstrations
System Archetypes as Hypothesis Templates
A template accepts almost any situation; the boundary and the observation decide what it predicts.
Part III
The formal machinery
- 124 demonstrations
Stocks, Flows, Sources, and Sinks
Every flow names two endpoints and a unit with a time base, and the accounting can then check itself.
- 134 demonstrations
Auxiliaries, Parameters, and Decision Rules
Four kinds of quantity share one notation, and each needs its own evidence and its own test.
- 144 demonstrations
Feedback and Loop Dominance
A model with two loops has a dominant loop at a moment, and the moment is part of the answer.
- 154 demonstrations
Nonlinearity and Lookup Functions
A lookup shows where its evidence ends; a fitted formula keeps answering after it has none.
- 164 demonstrations
Material and Information Delays
Two delays with the same mean behave differently, and where a delay sits matters as much as how long it is.
- 174 demonstrations
Cohorts, Aging Chains, and Coflows
People are not interchangeable units, and the experience they hold moves when they move.
- 184 demonstrations
Events, Queues, Agents, and Hybrid Models
When an aggregate model and a queue are joined, the seam between them is part of the model.
- 194 demonstrations
Numerical Integration Is Part of the Model
The same equations give different answers under different solvers, steps and update orders.
Part IV
Models as software
- 254 demonstrations
Turn Models into Management Flight Simulators
A scenario runner is worth what its record can replay and what its constraints can catch.
Part V
The AI roles
- 294 demonstrations
The AI as Experiment Designer
Reduce the uncertainty that most changes the decision, at the least cost, without breaking anything.
- 304 demonstrations
The AI as Policy Searcher
Rank by the worst case among the policies that satisfy every constraint, and say what was excluded.
Part VI
Cases, calibration, and capstone
- 324 demonstrations
Growth Can Destroy the Engine of Growth
A reinforcing loop can consume the capacity that sustains it, and the warning is a ratio nobody plots.
- 334 demonstrations
Technical Debt as a Stock
Debt is a stock nobody can count, and the review window decides which policy looks wise.
- 344 demonstrations
Hybrid Case: Hospital Capacity and Patient Flow
A policy can improve the average and fail one group, and only a per-group table shows it.
- 354 demonstrations
Fitting Is Not Confirming
A fit is the answer to a search, and the holdout and the choice of knob decide what it is worth.
- 364 demonstrations
Elective Backlogs as a Stock
A waiting list is a level, and the chapter fits one to a public record without forecasting it.
- 374 demonstrations
Hiring Is a Pipeline, Not a Number
A hiring target buys heads, and capability follows a ramp the record barely constrains.
- 384 demonstrations
Capacity Arrives When the Price Has Gone
A loop with two delays and nothing outside it can swing like a public record, which proves little.
- 394 demonstrations
Delay Is a Curve, Not a Line
Taxi-out rises with load while the quoted delay falls, and a cap can only be priced on the curve.
Notebooks on GitHub
Every chapter has a Jupyter notebook that reproduces its models and figures.