Phase 4 · Improve
A3 problem solving: the method, section by section
An A3 tells the story of a problem and its solution on a single sheet: background, current condition, goal, causes, countermeasures, plan and follow-up. The one-page limit forces clear thinking.
In short
A3 problem solving is a structured method, developed at Toyota, that sets out a problem, its root cause, the countermeasures and their follow-up on a single A3 sheet, following the Plan-Do-Check-Act (PDCA) cycle.
What it is
The name comes from the paper size. The left side holds the Plan: background, current condition, goal and root cause analysis. The right side holds the countermeasures, the implementation plan and the follow-up, which cover Do, Check and Act.
The sheet matters less than the conversations around it. One person writes it, but each section is checked with the people involved and with a mentor, who asks questions rather than giving answers.
When to use it
- For medium-sized problems: too big for a quick fix, too small for a full DMAIC project.
- When the analysis and the decision have to be shared with management on one page.
- To train people in structured problem solving, with a mentor reviewing each section.
How to do it, step by step
- 1Describe the background. Why this problem matters now, and to whom. Two or three lines.
- 2Show the current condition with data. What happens today, measured. A simple chart or a sketch of the process says more than a paragraph.
- 3Set the goal. From where to where, and by when. A figure the team can check.
- 4Analyse the root cause. With an Ishikawa diagram or the 5 Whys, on the sheet itself. Only causes confirmed with facts move forward.
- 5Propose countermeasures and a plan. One countermeasure per root cause, each with an owner and a date.
- 6Follow up and adjust. Compare the result with the goal. If it holds, standardise; if not, go back to the analysis.
Worked example
Case: a plant that wants new operators to reach standard output sooner.
| Background | New operators take too long to reach standard output, and many leave in their first months. Each departure means recruiting and training again. |
|---|---|
| Current condition | A new operator takes 14 weeks to reach standard output. 4 of the last 11 new operators left within six months. |
| Goal | 9 weeks to standard output, and six-month attrition of 15% or less, by 30 September. |
| Root cause analysis | There is no documented training path, so operators learn by imitation. The buddy changes with the shifts, so nobody follows each operator’s progress. |
| Countermeasures | A five-stage training path for each station. A fixed buddy on the same shift for the first eight weeks. A weekly progress review. |
| Implementation plan | Training path: training manager, end of May. Fixed buddy rule: shift leaders, from June. Weekly review: training manager, from June. |
| Follow-up | Weeks to standard output and attrition checked every month for the operators who started from June. A control plan keeps the new standard in place. |
Common mistakes
- Starting from the solution and filling in the left side to justify it.
- Too much text: if it does not fit on the sheet, the thinking is not clear yet.
- A current condition with no data, only opinions.
- Writing it alone, without checking each section with the people involved.
Frequently asked questions
Why is it called an A3?
Because it fits on one sheet of A3 paper, the size of two A4 sheets side by side. The limit is deliberate: it forces the author to keep only what matters.
Is A3 the same as PDCA?
An A3 is a way of writing down one PDCA cycle. The left side is the Plan; the right side covers Do, Check and Act.
A3 or DMAIC: which one should you use?
An A3 suits a problem one person can lead in a few weeks. DMAIC suits larger problems that need a team, deeper data analysis and several months. A DMAIC project can also be summarised on an A3.