White Belt · 12 min
The 4% problem: how much of your process is actually worth paying for
After this you can
- classify a process step as value-add, business-necessary non-value-add, or waste.
- calculate the value-add ratio of a process from its step times.
The problem
A patient arrives at an outpatient clinic at 09:00 and is seen at 10:22. Eighty-two minutes. When the team observed that morning properly — stopwatch, no interpretation — twenty-four of those minutes involved anyone doing anything for the patient. The other fifty-eight, the patient sat in a chair. Nobody was lazy. Nobody was doing a bad job. The staff were busy the entire time.
The idea
Work splits into three kinds, and the split is decided by the customer, not by how hard the work feels:
- Value-add — the customer would pay for it, it changes the thing, and it is done right first time. The consultation. The triage assessment.
- Business-necessary non-value-add — the customer would not pay for it, but you cannot legally or safely stop doing it. Confirming identity before treatment.
- Waste — everything else. Waiting. Rework. Moving things that did not need moving.
The value-add ratio is simply how much of the total elapsed time was value-add:
\text{VA ratio} = \frac{\sum \text{value-add time}}{\text{total lead time}}Note what is in the denominator: lead time, the whole clock from start to finish — not the time your team was busy. This is the distinction that makes the number useful. Measure "how much of our working time was productive" and you will get a comforting number. Measure "how much of the customer's wait was worth it" and you get the truth.
In most office and service processes the honest answer is somewhere between 1% and 10%. That is not a sign of a badly run organisation. It is the normal condition of any process nobody has deliberately designed for flow — and it is why improvement work has such large returns available to it.
Worked example
Here is the clinic morning, step by step. Each step is tagged from direct observation.
| Step | Minutes | Patient being served? |
|---|---|---|
| Arrive and join queue | 12 | waiting |
| Give name at desk | 1 | served |
| Wait for record retrieval | 8 | waiting |
| Confirm details | 3 | served |
| Wait for triage nurse | 17 | waiting |
| Triage assessment | 6 | served |
| Wait for room | 21 | waiting |
| Consultation | 14 | served |
Total lead time = 12 + 1 + 8 + 3 + 17 + 6 + 21 + 14 = 82 minutes
Now classify. "Served" is not automatically value-add — apply the customer test to each:
- Give name at desk (1 min) — the patient would not pay for this. The clinic needs it. Business-necessary NVA.
- Confirm details (3 min) — same. Business-necessary NVA.
- Triage assessment (6 min) — this changes the patient's care. Value-add.
- Consultation (14 min) — this is what they came for. Value-add.
- All four waits (58 min) — waste.
VA ratio = (6 + 14) / 82 = 20 / 82 = 0.243924.4%. Better than most, because a consultation is long relative to the waits.
Now the question that matters. If you halved the consultation time — worked twice as fast — you would save 7 minutes of an 82-minute wait. If you removed the 21-minute wait for a room, you save 21 minutes and change nothing about how anyone works.
The waiting is where the time is. It nearly always is, and it is nearly always the part nobody is measuring.
Dataset: ds-clinic-intake — the same data loads in the tool below, so you can reproduce every figure here yourself.
Your turn
Open the Waste Walk tool with this dataset loaded. Tag each step yourself, then compare.
Two things to try:
- Tag Confirm details as value-add and watch the ratio move. Decide whether you can defend that classification to the patient.
- Now retag Wait for room from waste to business-necessary. Watch what does and does not move: the waste total falls, the value-add ratio does not budge at all, because the denominator is still every minute the patient was there. Reclassifying changes the report and changes nothing about the morning. Only removing those minutes would — and no dropdown can do that.
Waste Walk
practiceClassify every step. Apply the customer test each time — would they pay for this? Effort and skill are never the test.
| Step | Min | Classification | Waste category |
|---|---|---|---|
| Arrive and join queue | 12 | ||
| Give name at desk | 1 | ||
| Wait for record retrieval | 8 | ||
| Confirm details | 3 | ||
| Wait for triage nurse | 17 | ||
| Triage assessment | 6 | ||
| Wait for room | 21 | ||
| Consultation | 14 |
Lead time
82 min
Value-add
0 min
Value-add ratio
0%
Waste
82 min
8 non-value-add steps have no waste category. Categorising them is what turns "this is waste" into a specific thing you can change.
How this is calculated
Value-add ratio = value-add time ÷ total lead time. The denominator is the whole clock, including every wait — not the time the team was busy. That distinction is what separates “how busy were we?” from “how much of the customer’s wait was worth it?”
- Value-add — The customer would pay for it, it changes the thing, and it is right first time.
- Business-necessary — The customer would not pay for it, but you cannot stop doing it.
- Waste — Everything else.
Source: Rother & Shook (1999), Learning to See; the eight wastes from Ohno (1988), Toyota Production System, Ch.3.
- Transport — moving the product
- Inventory — work sitting and waiting
- Motion — moving the person
- Waiting — work exists, nothing is happening to it
- Over-production — more, or sooner, than the next step needs
- Over-processing — beyond the customer requirement
- Defects — rework, correction or scrap
- Unused talent — the people doing the job were never asked
Check yourself
No hints. Wrong answers are explained, not softened.
A bank customer waits 40 minutes for a mortgage decision. A credit check takes 4 minutes and is legally required before lending. How should the credit check be classified?
A process has steps of 5, 30, 8 and 2 minutes. The 5-minute and 2-minute steps are value-add. What is the value-add ratio?
A team reports their value-add ratio improved from 6% to 9%. Lead time did not change. What most likely happened?
Apply it
You are asked to look at a purchase-order process. Observed: request raised (2 min), waits in a manager's inbox (3 days), approved (1 min), waits in finance queue (2 days), PO issued (4 min).
Your sponsor wants the team trained to "process POs faster". Write two or three sentences saying what you would measure first and what you would say to the sponsor.
Your answer is reviewed against a rubric, not matched to a keyword.
Worth remembering
What is in the denominator of the value-add ratio?
Total lead time — the whole clock from start to finish, including every wait. Not the time the team was busy.
The three tests a step must pass to be value-add
The customer would pay for it; it changes the product or service; it is done right first time. All three, not any one.
Can you do this now?
Rate yourself honestly. We compare your rating with how you actually answered — the gap is more useful than either number alone.
I can classify a process step as value-add, business-necessary non-value-add, or waste.
I can calculate the value-add ratio of a process from its step times.
Your rating is recorded alongside your drill results. Neither alone marks the competency as met.