Glossary

Terms this book uses in a specific sense, including several it uses differently from common practice. A book about definition that does not define its own vocabulary would be making its own point against itself.

Assignable cause. Variation in a process traceable to a specific, findable, removable event. Shewhart's term; the modern equivalent is special cause. Distinguished from chance cause, and the distinction is the whole of statistical process control. Responding to a chance cause as though it were assignable is tampering, and it increases variation.

Atomicity. The property of a value being indivisible for the purposes of a system. Not a property of the value itself: any value decomposes further for some purpose, which is why deepest identifiable condition names nothing on its own.

Attention budget. The premise that deliberate thought is scarce, non-renewable within a day, and spent by every claim on it whether or not the claim was worth making. Whitehead's cavalry charges and Simon's poverty of attention are the same budget stated seventy years apart. The eighth rule was rewritten because its original form treated this budget as unlimited.

Automation bias. The tendency to accept what an automated system offers, including against contrary evidence, and to fail to act where the system did not prompt. The second form is less visible and probably more common.

Capture versus custody. Getting a fact out of a head is a one-time act; keeping it true is a permanent liability. The creed priced the first and not the second, which is one of the five routes to the decay problem.

Chance cause. Variation belonging to the process itself, always present, not traceable to anything in particular, producing a stable spread. Also common cause. It cannot be removed by working more carefully, only by changing the system.

Compiled. Of a decision or routine: solved once, then run without being re-solved. A compiled routine has an author whose reasoning is buried in it and unavailable to inspection, which distinguishes it from a reflex, which was never solved by anybody.

Contact. A person's engagement with a situation, as distinct from friction. Both arrive as work a person has to do. Removing friction is a gain; removing contact costs a capability that had no name.

Derived value. A fact computed by a system from other facts rather than supplied by a person. Three states matter: certain, probable, and ambiguous, and a system that renders all three identically will have its guesses accepted as certainties.

Domain, ordered and unordered. From Cynefin. In the ordered domains cause and effect are knowable, whether or not currently known, and rules work. In the complex domain they cohere only in retrospect, and imposing order suppresses the variation that is the only available instrument. The creed is an ordered-domain method throughout.

Drift. Change in a method by increments nobody decided. Distinguished from tampering, which is change somebody decided badly. Drift is the harder problem, because it leaves no evidence and because every instrument for detecting it is built from the process's own recent history, which drifted along with it.

Friction. Work a person does that the system could have done. Pure cost, removable.

Joint optimization. From sociotechnical systems theory: the finding that a work system has a technical and a social dimension, that they interact, and that optimizing either alone reliably underperforms optimizing both. The thirteenth rule exists because the original creed had no social term at all.

Legibility. Scott's term for the property that lets a central authority see and therefore manage something. Achieved by simplification, and the simplification drops things that turn out to have been load-bearing.

Metis. Scott's term for practical knowledge built by experience, particular to its setting, adaptive to circumstances that shift. Contrasted with techne, which is codifiable and universal. Metis is what an abstraction cannot hold.

Operational definition. A definition consisting of a test, a criterion for judging the test's result, and a yes-or-no decision. Deming's structure. A term is treated in this book as defined when it has all three, which is a stopping rule adopted for convenience rather than a solution to the definitional regress.

Override rate. How often people depart from a rule that governs them, where the departure is possible and recorded. The only instrument that measures how wrong a rule is from inside the system running it. Silent about rules people have stopped consulting.

Manual-decision register. A record of decisions deliberately left manual, with the date, the reason, and who decided. Exists because the boundary rule is the only one in the creed that builds nothing, so without a register the creed systematically over-reports its own construction and under-reports its own restraint.

Poka-yoke. Error-proofing: making a mistake physically impossible rather than asking people to be careful. From the Toyota tradition.

Pull and push. Two separate vocabularies that collide. In Lean, pull governs work and is the virtue. In this creed, push governs information and is the virtue. Both say nobody should be buried in material they did not request and nobody should have to hunt for what they need. Push the signal, pull the work.

Quantified. In this book: having stated inputs, a stated mapping from inputs to output, and a result reproducible by somebody who is not you. Numbers are one way to get there and often not the best one. A thing is quantified when it has stopped depending on who is doing it.

Reflex. A response that was never solved by anybody and arrived installed. Distinguished from a compiled routine, which was solved once.

Requisite variety. Ashby's law, that a regulator needs at least as many distinct states as the situations it must handle. Used here as a floor on definitional depth: a definition with fewer distinctions than the world produces will answer some situations with an action built for a different one.

Scope failure. A system that is accurate about what it measures and blind to a quantity nobody thought to measure. Distinguished from an accuracy failure, which measurement can catch. Scope failures are invisible to measurement by construction, and the only defenses are slow.

Standing answer. A decision converted into a rule that runs without being re-decided. Every rule in this creed produces one, and every standing answer silently contains the state of the world at the moment it was made.

Tacit knowledge. Knowledge that cannot be told by the person who has it. Polanyi's argument is that tacit knowing is a dimension of all knowing rather than a separate category, which is why the seventh rule had to be rewritten to claim less.

Tampering. Adjusting a process in response to a fluctuation that belongs to the process. Feels responsible, measurably increases variation.

The system. As in if it lives in your head, it should live in the system: the record of the business, the place a second person can go without asking the first. The quotation marks in the original were a hedge, and the reconciled version drops the word in favor of a trace outside your head, because a system holds artifacts and artifacts are not knowledge.