💡 Question 3 — Langley et al. · The Improvement Guide

Why nothing changes — and what actually will

You have the data. You can see the system is not improving. You have tried things — training, new processes, more resource, a new target. The Bootstrap CUSUM chart shows no confirmed step change. This page explains why that happens — and what kind of intervention will actually move the line.

The tampering trap. If you have the right kind of initiative — ideally a Level 3 structural intervention — the most dangerous thing you can do is abandon it before it has had time to work. Deming called this tampering: changing a process in response to variation rather than genuine evidence of structural change. Bootstrap CUSUM is the tool that tells you when to wait and when to act — because it distinguishes between genuine step change and noise. Start here to understand the full picture ›

Three signals that tell you more effort is not the answer

Most persistent problems are treated as effort problems. Work harder. Try again. The next attempt will be different. But when any of the following three signals are present, the problem is structural — and structural problems do not respond to effort. They require a different kind of intervention altogether.

1
The same failure shape keeps recurring

Despite different attempts, the failure keeps happening in roughly the same way. Random bad luck produces random failure. Structural causes produce consistent failure patterns. If you can describe the shape of the failure before it happens — it is structural.

2
Effort increases — results do not

Deming called this working harder within a flawed system. If people are working harder than before and the outcome is the same or worse, the constraint is not effort — it is the system. No amount of trying harder moves a result that is structurally limited.

3
The solution feels obvious inside — invisible outside

When the people closest to the work are convinced the solution is clear and the outside world keeps failing to see it, there is usually a jobs mismatch — the solution addresses a problem the mainstream does not recognise as its own.

The diagnostic test — one question before you proceed

If we doubled our effort from tomorrow, would the result improve — or would we produce the same outcome twice as fast?

If the honest answer is the second: stop. Diagnose. The constraint is not effort. Find what the constraint actually is — then direct persistence at the right thing, not at repeating the same action with more energy.

From diagnosis to action

Recognising the signals above tells you that the system needs to change. The next question is how — precisely and systematically. The seven-step improvement method on this site takes you from listing symptoms, through root cause analysis and prioritisation, to a PDSA cycle verified by Bootstrap CUSUM. Each step builds on the diagnostic framework described on this page.

✅ The 7-step improvement method

A practical, structured cycle that closes the three most common improvement gaps: fixing the symptom instead of the cause, fixing the cause at the wrong level, and never verifying the fix worked. Read the full method →

Is the intervention deep enough to hold? — Joiner’s levels

Before designing any intervention, classify it. This is the question that determines whether a change will hold or revert. Most improvement programmes fail not because the intervention was wrong but because it was aimed at the wrong depth. A Level 1 or Level 2 intervention aimed at a Level 3 problem will produce temporary improvement followed by reversion, every time, regardless of how well it is implemented.

Bootstrap CUSUM is the arbiter. A Level 1 fix will show no confirmed step change — or a brief apparent improvement that reverts. A Level 3 structural change will show a confirmed sustained step change with statistical confidence.

Level 1
Fix the output

Firefighting. React to the problem after it has occurred. The system is unchanged. The problem returns. Bootstrap CUSUM will show no confirmed step change — because nothing structural has changed. Necessary in the short term. Insufficient as a strategy.

Level 2
Fix the process

A checklist, a protocol, a gate. Prevents this specific failure mode recurring. Does not change the underlying system that generated the process. May show a temporary step change before reverting when the broader system pushes back. The dementia diagnosis target is a Level 1–2 intervention inside an unchanged system.

Level 3
Fix the system

Change roles, decision rights, policies, structures. Durable because it works regardless of who is in the role and regardless of individual effort. Bootstrap CUSUM will show a confirmed sustained step change — the signal that the system has genuinely moved. The ULEZ air quality improvement is a Level 3 system change.

Level 3 Deep
Fix the root

Change the mental model that generated the system design. The hardest level and the highest leverage. Without this, every Level 3 structural fix will be quietly undermined because the leader’s behaviour gravitationally recreates the old system. Joiner’s fourth generation management is entirely about this level.

The policy shortcut — the most underused Level 3 intervention. A written, signed, dated rule that governs a category of decisions permanently. It costs one afternoon to write and nothing to implement. Its effect is permanent because it changes every future instance of that decision, not just the one in front of you today. Before designing a complex structural change, always ask: could a policy decision achieve the same result?
Deming’s test — applied to every proposed intervention

“By what method will this intervention produce the improvement we are predicting?”

If the answer is because people will try harder or because the target is higher — it is not a method. It is a goal without a method. Deming spent forty years showing why goals without methods produce distortion, not improvement. Go back to the system and find the Level 3 structural change that makes the improvement happen regardless of individual effort. Joiner’s levels explained with worked examples ›

Look for what is already working — before building anything new

Chip and Dan Heath (Switch, 2010) and Jerry Sternin’s Positive Deviance framework make the same observation: the answer to most persistent problems is already present somewhere in the system. Someone, somewhere, with the same resources and the same constraints, is already achieving the outcome you are trying to produce.

In twelve years of the UK dementia challenge, Kent’s integrated care model recovered from COVID at nine times the national average rate — using the same NHS workforce, the same population, the same disease. The answer was already there. No one was looking for it. The improvement programme was designed to create new solutions rather than find and scale the Bright Spot that already existed.

Where in this system is performance significantly better — with no obvious explanation in additional resource?

The Bright Spot detection question. The positive outlier in the variation data is the structural answer waiting to be found.

What does the Bright Spot do that others do not?

The structural difference. This is the Level 3 intervention already running in one part of your system. Study it before designing anything.

If the specific people involved left tomorrow — would the better outcome continue?

Tests whether the Bright Spot is structural (scaleable) or personal (not automatically scaleable). Only structural Bright Spots transfer reliably.

Scale through discovery, not instruction. Sternin’s most important practical finding: a solution discovered from within the community is owned by the community. A solution brought in from outside is complied with and then abandoned when pressure increases. Help people find the Bright Spot themselves — do not present it to them.

How Bootstrap CUSUM and this method work together

They answer different questions. Used together they give a complete picture — from detection to diagnosis to action.

Question 2 — Langley et al. · Study phase of PDSA
Bootstrap CUSUM

Has a structural change occurred? Is this a genuine step change or noise? When should I wait — and when should I act?

Question 3 — Langley et al. · This method
The diagnostic method

Why has no structural change occurred? What level of intervention would actually produce the step change the chart is waiting to detect?

When Bootstrap CUSUM shows no confirmed step change after genuine improvement effort, apply the five-stage diagnostic method. Find the root cause or structural absence. Classify the intervention using Joiner’s levels. Design at Level 3 or deeper. Write a prediction. Then run Bootstrap CUSUM again — and watch for the step change the chart has been waiting to show.

▶ Run Bootstrap CUSUM on your own data — free, browser-based, any sector

See the diagnosis in practice

Each article below applies the full five-stage diagnostic method to a real system where improvement has stalled — showing what the Bootstrap CUSUM chart reveals, why the standard interventions did not produce structural change, and what would have.

🏥️ NHS Public Health

Dementia — twelve years of targets, no structural change

Two Prime Ministerial challenges, fifty commitments, £300m. The diagnosis rate barely moved from the 2012 target. The five-stage method identifies the root cause: a reactive system design and a single-node GP dependency. Bootstrap CUSUM confirms: one stage, no confirmed structural improvement.

🏥️ NHS Emergency Care

NHS A&E — four stages of structural decline

Bootstrap CUSUM applied to 15 years of monthly data. Not one policy intervention is detectable as a structural improvement. Four confirmed step changes — all downward. The constraint was never identified. The interventions were all Level 1 and Level 2.

💊 Patient Safety

Never events that never stopped

Declared “wholly preventable” in 2011. The engineering solution existed. Bootstrap CUSUM finds a flat process at 17.5 events per year. A Level 3 structural change was available and not made. The Level 2 guidance was issued and ignored.

🎯 Our mission

“Give people better tools and a better mental model to ask better questions about whether things have improved through structural change — and to understand why, when they haven’t.”

▶ Open the free tool ← Back to start here

Frameworks referenced on this page:

Joiner levels of fix — Joiner, B.L. Fourth Generation Management, McGraw-Hill, 1994 · By what method — Deming — Deming, W.E. Out of the Crisis, MIT Press, 1982; The New Economics, MIT Press, 1993 · Theory of Constraints — Goldratt, E.M. The Goal, 1984; It’s Not Luck, 1994 · Systems thinking · reinforcing loops — Meadows, D. Thinking in Systems, Chelsea Green, 2008; Senge, P. The Fifth Discipline, 1990 · Bright Spots — Heath, C. and Heath, D. Switch, Random House, 2010 · Positive Deviance — Pascale, R., Sternin, J. and Sternin, M. The Power of Positive Deviance, Harvard Business Press, 2010 · Model for Improvement — Langley, G.L. et al. The Improvement Guide, 2nd ed., Jossey-Bass, 2009