Methods reference

Lean methods and tools: what each is for, and when to use it in an office

By KaizenProof · Updated 9 October 2026 · Last reviewed 9 October 2026

In short

Lean methods are the named routines of Kaizen and the Toyota Production System, each built for one kind of problem: PDCA to test a change, the 5 Whys to find a cause, an A3 to reason on one page, standard work to hold a gain, kanban to limit work in progress. Choosing the method from the problem, and not the other way round, is most of the skill.

This reference covers thirteen methods. Each entry gives a definition that stands on its own, when to use the method, when not to, how it applies to office work, and where it comes from, with sources.

Which Lean method fits which problem?

Start from the problem, then pick the method
The problem in front of you	Method	What you get
The same thing goes wrong every week and nobody knows why	5 Whys	A cause in a process, rule, tool or owner that someone can change
A problem with several causes, or one other people must agree to fix	A3	The facts, the cause, the plan and the check on one page
People describe the process differently	Gemba walk	What happens to one real item, as opposed to what should happen
A step looks unnecessary or clumsy	ECRS	The smallest change: remove, merge, reorder or simplify
You are about to change how work is done	PDCA	A prediction written first, and a check against it
A fix worked and then slipped back	Standard work and SDCA	The current best way, written down, with an owner who checks it
Too much is started and too little finished	Kanban	Visible work and a limit on how much is in progress
The same error keeps being typed or sent	Poka-yoke	A form, field or rule that makes the error hard to make
Work takes days though the effort is minutes	Value stream mapping	Where the work waits, and for how long
Nobody can find the current file, template or version	5S	One place for each thing, kept that way
Calm weeks, then a crush at month end	Heijunka	Work spread more evenly over the period
Errors are found late, by someone downstream	Jidoka	The right, and the means, to stop and fix at the source

Which methods find a cause and test a change?

PDCA

Also called: Plan-Do-Check-Act, Deming cycle, Shewhart cycle. PDCA (Plan, Do, Check, Act) is a four-step cycle that treats a change to how work is done as an experiment. You plan the change and write down what you expect, do it on a small scale, check the result against the expectation, then adopt, adjust or abandon it.

Use it when: Every time you change how work is done, however small the change. It is the frame the other methods sit inside.
Not when: When the plan has no prediction that could turn out wrong. Then it is a to-do list with a cycle drawn round it.
In office work: Run one cycle on one form, one report or one type of request for a week or a month. Predict something you can see without new measurement: the question no longer arrives, the form no longer comes back.
Where it comes from: It descends from Walter Shewhart's three-step cycle of 1939 and the four-step wheel W. Edwards Deming showed in Japan in 1950; the plan-do-check-act wording appeared in Japan in 1951 with no named author. Deming himself preferred plan-do-study-act. [1]

SDCA

Also called: Standardise-Do-Check-Act. SDCA (Standardise, Do, Check, Act) is the cycle for holding a way of working steady. You write the standard, work to it, check that it is followed and still gives the result, and act when it does not.

Use it when: After a change has held and become the normal way, and whenever results drift without anyone having changed anything.
Not when: When there is no agreed way of working yet. Write the standard first; and when the standard itself is the problem, go back to PDCA.
In office work: Give each written procedure an owner and a review date, and look at a few real cases on that date. Most office standards fail quietly because nobody is asked to look.
Where it comes from: SDCA is taught in the Kaizen literature as the companion of PDCA: one cycle keeps a standard, the other raises it. Kaizen Institute, the firm Masaaki Imai founded, teaches the two as a pair. We found no source we could check for who first named it, so we name nobody. [4]

5 Whys

Also called: five whys, why-why analysis. The 5 Whys is the practice of asking why a problem happens, then why about each answer, until you reach a cause you can change. Five is a guide and not a rule: the chain stops at a process, a policy, a tool or a missing owner, never at a person.

Use it when: For a recurring problem with one main line of cause that the people doing the work can trace from what they know.
Not when: When several causes interact, when the answers are guesses nobody can check, or when the error rate hides in volume and needs data. A chain reasoned out at a desk, with nobody going to look, sounds right and proves nothing.
In office work: Write each answer with the evidence for it: an email, a count, a screenshot of the form. In office work the chain usually ends at a form, a rule or an approval nobody owns.
Where it comes from: Taiichi Ohno described asking why five times in his book on the Toyota Production System, with the example of a stopped machine traced to a missing strainer. The habit is often credited to Sakichi Toyoda, though the sources we opened do not show where that credit comes from. In a 2003 talk Teruyuki Minoura, then a Toyota managing director, said the method often works less well than it should for lack of practical training: people answer by deduction where they should go and observe. [3][5][16]

A3

Also called: A3 report, A3 thinking. An A3 is one problem told on a single sheet: the background, the current state, the cause, the countermeasure, the plan and how the result will be checked. It is named after the A3 paper size, 297 by 420 millimetres.

Use it when: When a problem has more than one cause, crosses teams, or needs other people to agree before anything changes.
Not when: For a small fix one person can make today. Filling in the sheet then costs more than the problem.
In office work: Use it as the agenda for a conversation, not as a report to file. A page of text with no facts and no check is a memo, not an A3.
Where it comes from: The Lean Enterprise Institute describes it as a practice pioneered at Toyota, where it became the standard way to summarise problem solving, status reports and planning. [6]

Gemba walk

Also called: go and see, genba. Gemba is the Japanese term for the actual place where the work is done. A gemba walk is the practice of going there to grasp the current situation by watching and asking, before deciding anything.

Use it when: Before any analysis, and whenever two people describe the same process differently.
Not when: As an inspection or a tour. If people expect to be judged, they show you the procedure and not the work.
In office work: The place is an inbox, a spreadsheet and a queue. Follow one real item from request to done and write down each wait, each handoff and each re-entry of the same data.
Where it comes from: The word is Japanese; the Lean Enterprise Institute's lexicon translates it as actual place, gives the spelling genba, and pairs it with genchi gembutsu, go and see. [7]

ECRS

Also called: Eliminate, Combine, Rearrange, Simplify. ECRS stands for eliminate, combine, rearrange, simplify: four questions to ask of any step, in that order. Removing a step comes first because a step that is gone needs no improving.

Use it when: When you know which step causes the trouble and are choosing what to do about it.
Not when: Before you know the cause. Without one, ECRS turns into tidying whatever is easiest to reach.
In office work: Ask of each approval, copy and report: who uses this, and what would happen if it stopped? Automation is a fifth question, asked only after the first four.
Where it comes from: The four words come from the Job Methods course of the American wartime programme Training Within Industry, which taught people to improve a job by eliminating, combining, rearranging or simplifying its steps. Art Smalley, in a talk published by the Lean Enterprise Institute, traces the first step to that course and the last to the work-simplification teaching of Allan Mogensen. [8][17]

Which methods keep work stable and visible?

Standard work

Also called: standardized work. Standard work is the best way the team knows today to do a task, written down precisely enough to follow. It is the baseline improvement starts from: without it, nobody can tell a change from ordinary variation.

Use it when: As soon as a change has held, and for any task done by more than one person or handed over at holidays.
Not when: For work that is different every time and calls for judgement. Write the few fixed points, such as checks and handoffs, and leave the rest.
In office work: One page: purpose, steps with the key point of each, known exceptions, owner, review date. A manual nobody opens is not standard work.
Where it comes from: In the Toyota Production System, as the Lean Enterprise Institute's lexicon describes it, standardized work is built on three elements: takt time, the work sequence and the standard inventory needed to keep the process running. An office standard as described here keeps the written current method and leaves out the pace and the stock, which makes it closer to what that lexicon calls a job instruction sheet than to standardized work in a plant. [9]

5S

Also called: seiri, seiton, seiso, seiketsu, shitsuke. 5S is a routine for keeping a workplace in order, named after five Japanese words usually translated as sort, straighten (or set in order), shine, standardise and sustain. Its purpose is that anything out of place, missing or abnormal is obvious at a glance.

Use it when: When people lose time finding the current file, template, login or version, or when two copies of the truth exist.
Not when: As a tidy-up campaign on its own. Order that serves no flow of work decays within weeks.
In office work: Apply it to shared drives, templates and inboxes: one place for each thing, one current version, a named owner, and a date when old material is cleared.
Where it comes from: The five words come from Japanese manufacturing. The Lean Enterprise Institute notes that Toyota traditionally speaks of only four S, and that some practitioners add a sixth, for safety. [10]

Kanban

Also called: kanban board, pull signal. A kanban is a signal that authorises work: in a factory, a card that tells the previous step to make or move a set quantity. In knowledge work it has come to mean a board that makes work visible and limits how much is in progress at once.

Use it when: When too much is started and too little finished, or when nobody can see what is stuck.
Not when: When the board has no limits. A board that only lists tasks shows the overload without reducing it.
In office work: Three columns are enough to start: waiting, in progress, done. Set a limit on in progress, and treat a full column as a reason to help finish and not to start.
Where it comes from: The word is Japanese for sign or signboard. Taiichi Ohno developed the system at Toyota after the company studied how supermarkets restock shelves, and Toyota applied it in its main plant machine shop in 1953. Its use for knowledge work came from software teams in the 2000s. [11][18][19]

Poka-yoke

Also called: mistake-proofing, error-proofing. Poka-yoke is any feature of a process that prevents a mistake, or makes it obvious the moment it is made. It changes the design of the work so that doing it right is the easy path.

Use it when: When the same slip recurs although people know the rule: a missing reference number, a wrong date format, a file sent to the wrong list.
Not when: When the error comes from an unclear rule. Fix the rule first; and do not add a control that people will have to work around.
In office work: A required field, a drop-down in place of free text, a template that will not save without an owner, a payment that cannot go to an unverified account.
Where it comes from: Shigeo Shingo formalised the idea and applied the term to industrial processes in the 1960s. It was first called baka-yoke, fool-proofing, and renamed to the milder poka-yoke. [20]

Which methods come from the factory floor, and do they transfer?

These three were designed for production lines. Each carries an idea an office can use, and each is easy to misapply when copied with its factory vocabulary intact.

Value stream mapping

Also called: VSM, material and information flow diagram. Value stream mapping is drawing every step that material and information pass through to bring one product or service from request to delivery. A current-state map shows the flow as it is, with its waits; a future-state map shows the flow you intend to build.

Use it when: When the delay is between teams and tools, not inside one task, and the people who own each part can map it together.
Not when: For a problem inside one person's task, or when nobody with the authority to change the flow takes part. The map then becomes a poster.
In office work: Map one type of request, with real times: how long each step is worked on and how long the item waits before it. Skip the factory symbols; boxes, arrows and two numbers per step are enough.
Where it comes from: The Lean Enterprise Institute says Toyota developed the tool, which it calls a material and information flow diagram. It reached a wide audience through the workbook Learning to See by Mike Rother and John Shook. [12][13]

Jidoka

Also called: autonomation, automation with a human touch. Jidoka means giving machines and people the ability to detect that something is abnormal and to stop the work at once. It builds quality in at the step where the work is done, where inspection would only find the error later.

Use it when: When errors are discovered downstream, after more work has been built on top of them.
Not when: Where stopping carries no way to get help. A stop that nobody answers teaches people not to stop.
In office work: Let the person who receives incomplete input send it back with the reason, at once, and count the reasons. A form that refuses a missing field is a poka-yoke, one device in its service; jidoka is the wider rule that the work stops and someone responds.
Where it comes from: Toyota names it as one of the two pillars of its production system, with just-in-time, and traces it to the looms of Sakichi Toyoda, whose power loom of 1896 carried a device that stopped it when the weft thread broke. The Lean Enterprise Institute's lexicon dates the idea to the early 1900s. [2][14]

Heijunka

Also called: levelling, production levelling. Heijunka is levelling the type and the quantity of work over a fixed period, so that each day carries a similar load and mix. It replaces large batches and end-of-period peaks with a steady rhythm.

Use it when: When demand is predictable in total but arrives, or is processed, in lumps: month-end closes, weekly batch approvals, quarterly reviews.
Not when: When the work truly arrives at random and must be answered at once, as an incident does. Then you need spare capacity, not a schedule.
In office work: Move what can move: reconcile weekly where you now reconcile monthly, approve daily in place of a Friday batch, spread reviews across the quarter.
Where it comes from: It is part of the Toyota Production System; the Lean Enterprise Institute's lexicon defines it as levelling both the volume and the mix of production. [15]

In what order should an office team learn these methods?

Start with the three that need nothing but a problem and a pen: a gemba walk to see the work, the 5 Whys to find a cause, and PDCA to test one change. Add standard work when the first change has held, so that it stays. Reach for an A3 when a problem is too big for one chain of whys. The factory-floor methods can wait until a problem asks for them.

Each of these has a blank worksheet with a filled-in example: the 5 Whys template, the A3 problem solving template, the PDCA template and the standard work template. Short definitions of every term on this page are in the Kaizen glossary; where the methods come from is told in the history of Kaizen and Lean, and the books that describe them are in the reading list.

Sources

Each numbered source was opened and compared with the text of this page on 9 October 2026. A number in square brackets after a statement points to the source it rests on.

Try it on your own work

Pick one task that wastes your team's time every week. Describe it in a sentence; KaizenProof names the waste, asks why until you reach the cause, and writes the fix. No account is needed to start.

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