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Where does the time actually go between the steps?

Map the steps and the waiting between them on one scale, so the gaps that carry most of the elapsed time stop being invisible.

Process Map · measure · White Belt · free, no account needed

Use this when

  • A process takes days but the work in it takes minutes
  • You have a flowchart and it has not helped you find anything
  • Two teams disagree about which step is the slow one

Process Map

sandbox

Record the work and the waiting. A flowchart has no notation for the gaps, which is where nearly all the elapsed time in office work lives.

  • Receive invoice3 min work · 0 min waiting
  • Match to purchase order8 min work · 8.0 h waiting
  • Resolve mismatch25 min work · 2.0 d waiting
  • Obtain approval4 min work · 1.0 d waiting
  • Release payment6 min work · 16.0 h waiting
Solid: working. Hatched: waiting. Drawn to one scale — which is the point. Waiting is 99% of the elapsed time.
Process steps with who performs them, working time, waiting time before the step, and classification.
StepWhoWork (min)Waiting before (min)ClassificationWaste category

Lead time

4.0 d

Working time

46 min

Waiting

4.0 d

Value-add ratio

0.24%

The largest removable category is waiting at 5760 minutes — 99.2% of total lead time. Removing it would do more than speeding up the value-add work.

Working twice as fast on the value-add steps would save 7 minutes. Removing the largest waste category would save 5760. The waiting is where the time is — it nearly always is, and it is nearly always the part nobody measures.

1 non-value-add step has no waste category. Categorising them is what turns "this is waste" into a specific thing you can change.

How this is calculated

Waiting is treated as a step in its own right, so it lands in the lead time and in the waste totals rather than being a property of a box that the arithmetic never sees. Value-add ratio is value-add time ÷ total elapsed lead time, including every wait — not the time the team was busy. Measuring against working time answers “how busy were we?” and produces a comforting number.

The arithmetic is the same function the Waste Walk uses, so the two tools cannot disagree about a value-add ratio.

Source: Rother, M. & Shook, J. (1999), Learning to See; George, M. et al. (2005), The Lean Six Sigma Pocket Toolbook — process cycle efficiency.

How this is calculated

Waiting is modelled as a step in its own right so it enters the lead time and the waste totals. Value-add ratio = value-add time / total elapsed lead time, including every wait — never divided by the time the team was busy. The arithmetic is the same analyseValueStream function the Waste Walk uses, so the two tools cannot disagree.

Source: Rother, M. & Shook, J. (1999), Learning to See; George, M. et al. (2005), The Lean Six Sigma Pocket Toolbook, process cycle efficiency.

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