The short answer
Performance and process improvement is the largest domain on the CPHQ exam: 27 of the 125 scored questions, or 21.6 per cent of your result. CPHQ performance improvement items seldom ask for a definition of PDSA or DMAIC. They give you a short scenario and ask which method fits it, which tool comes next, or why a gain did not hold. Method selection, not vocabulary, is what earns the marks here.
What does the performance and process improvement domain cover?
NAHQ's published content outline gives this domain 27 of the 125 scored items. The paper is 140 questions, 15 of them unscored pretest items you cannot identify while sitting, with a maximum of three hours. Scoring is scaled from 200 to 800 and 600 passes. That is why I tell people to start here: the largest domain is the one a weak performance is hardest to compensate for elsewhere. The weighting of all seven domains is the first thing worth memorising.
The domain covers the whole arc of improvement work: choosing a method, defining the problem and its measures, mapping the process as it is actually performed, finding causes, testing changes at a scale small enough to learn from, then holding and spreading the gain. It does not cover the statistical interpretation of data, which sits in health data analytics, or harm prevention, which sits in patient safety. Those borders matter more than they look, because a large share of the items candidates get wrong are items they answered from the wrong domain.
Across the exam the item types split 23 per cent recall, 57 per cent application and 20 per cent analysis. Here it feels heavier still towards application: you are handed a team, a problem, a fragment of data and a constraint, and asked what to do next.
Which CPHQ performance improvement concepts does NAHQ test?
The Model for Improvement and PDSA
Three questions frame the model: what are we trying to accomplish, how will we know that a change is an improvement, and what changes can we make that will result in improvement. Underneath sit Plan-Do-Study-Act cycles. The point most candidates miss is that a cycle is a learning device, not a pilot. You run it small, on one clinician for one shift if that is what it takes, because a cycle that fails cheaply on Tuesday tells you what to change by Thursday. Cycles then ramp.
DMAIC and the Six Sigma sequence
Define, Measure, Analyse, Improve, Control. DMAIC assumes an existing process producing too much variation or too many defects, and it front-loads measurement: you define the defect operationally, establish baseline capability, and only then look for causes. Its distinguishing feature is the Control phase, which is a documented handover of the improved process to the people who own it. If a stem mentions defects, variation, a charter, a sponsor and existing data, DMAIC is usually the intended answer.
Lean, waste and value-stream mapping
Lean starts from value defined by the patient and removes everything else: waiting, motion, transport, over-processing, inventory, defects, overproduction and unused staff capability. Its flagship tool is the value-stream map, which follows a care journey across departments and records, for each step, how long the work takes and how long the patient waits. The number it produces is the proportion of total lead time that is value-adding, and in most hospital processes that proportion is humbling.
Keep three mapping tools separate. A process map shows steps and decision points inside one process. A value-stream map shows the end-to-end journey with time and information flow attached. A workflow or spaghetti diagram shows physical movement. Exam items exploit the confusion between the first two constantly.
Driver diagrams and the tools that belong before the intervention
A driver diagram connects an aim to the primary drivers that would have to change for it to move, then to secondary drivers, then to change ideas. It makes a team's theory visible and testable. SIPOC sets the boundaries before you map, Pareto tells you which contributor to attack first, and a run chart establishes what the process was doing before you touched it. The most reliable trap in this domain is a stem in which the team already has an intervention: the correct answer is almost always a tool that would tell them whether it is the right one.
Cause analysis used for improvement rather than for safety
Fishbone diagrams, five whys and Pareto charts appear in both this domain and patient safety; the trigger separates them. In improvement you apply them to a chronic performance gap nobody has been harmed by yet; in safety, after an event. Read the stem for whether harm has occurred.
Spread and sustainability
Sustainability is a control plan with a named owner, standard work describing the new process, the measure moved into routine departmental reporting, and an audit schedule that thins rather than stops. Spread is separate work, not an announcement: each new unit needs local adaptation, its own small tests and someone accountable. When a stem says the gain eroded after six months, it is testing sustainability, and the answer is rarely more education.
An improvement project of mine that under-delivered, and why
Some years ago I led a project on outpatient pharmacy waiting time in a large public hospital. Patients queued for most of a morning to collect medicines. We had a sponsor, a willing pharmacy team and permission to change the layout, and within three weeks we had opened a second dispensing window and rostered an extra pharmacist to it. The median wait fell, visibly, for about a month. Then it climbed back to roughly where it started, and by the following quarter the second window was being used as a store cupboard. We had solved the part of the process we could see from the counter. When we finally mapped the whole stream, prescription to medicine in hand, the constraint was upstream: prescriptions arrived in batches after ward rounds, waited for verification by a single pharmacist who was also covering a ward, then hit dispensing at once. The second window idled all morning and drowned after eleven. We had added capacity behind the bottleneck, which only moves the queue. Three errors compounded it. We tracked the average wait rather than the distribution, so the long tail that generated every complaint was invisible. We never wrote an operational definition of when the wait started, so two people counting the same morning got different numbers. And we had no control plan, so when the pharmacist was pulled to cover leave, nobody noticed. The second attempt was less impressive and worked. We staggered verification so it ran continuously instead of in batches, moved the measure into the pharmacy's own monthly report with the department head as owner, and tracked the ninetieth centile alongside the median. The gain was smaller than the one we announced the first time. It was still there two years later.
[INSERT PRACTITIONER STORY: confirm or replace the passage above with your own project, and check every figure. Keep the shape — first change, apparent gain, real constraint, what made attempt two hold — and keep it non-identifying.]
PDSA, DMAIC, Lean or a hybrid: which method fits the problem?
Items here turn on method selection, and the deciding factor is the shape of the problem, not the size of the organisation.
| Method | Use it when | Core sequence | Typical stem cue | Where candidates go wrong |
|---|---|---|---|---|
| Model for Improvement with PDSA | The change is uncertain, the team can test locally, and learning is wanted quickly | Aim, measures, change ideas, then repeated cycles that ramp in scale | "Trial a change on one ward before rolling it out" | Treating a cycle as a pilot that must succeed, and starting hospital-wide |
| DMAIC | An existing process produces measurable defects or variation and the fix is not obvious | Define, Measure, Analyse, Improve, Control | "Defect rate", "variation", "baseline data", a chartered project | Skipping to Improve without a baseline; treating Control as a report |
| Lean | The problem is delay, handoffs, rework or movement, and it crosses departments | Define value, map the value stream, create flow, establish pull | "Waiting", "queue", "moved between four areas", "duplicate entry" | Calling any process map a value-stream map; cutting steps without finding the constraint |
| Lean Six Sigma | Both flow and variation are problems and trained belts already exist | DMAIC structure with Lean tools inside Analyse and Improve | "Green belt", "black belt", a formal project pipeline | Assuming the hybrid is the better answer because it contains more words |
| Rapid improvement event | Scope is narrow and the people who do the work can be released together | Concentrated multi-day mapping, redesign and trial | "Three-day workshop", "taken off the roster" | Ending with no owner, no measure and no follow-up audit |
Three exam-style questions, worked through
These are written in the NAHQ style rather than taken from any exam. Decide what is being asked before the distractors work on you.
Question 1: choosing the method
A medical ward's pressure injury rate has been stable but above target for two years. The unit manager proposes a repositioning prompt on the electronic record and wants to know within a month whether it helps before asking for it hospital-wide. Baseline data exist and the team is confident about the change. Which approach should the quality professional recommend?
- Charter a DMAIC project with a green belt
- Run sequential PDSA cycles on one shift, then one ward
- Complete a failure mode and effects analysis of repositioning
- Construct a value-stream map of the admission process
Answer: 2. The stem gives a specific change idea, a single unit, a short time frame and a wish to learn before spreading: the use case for small ramped cycles. Option 1 fails because DMAIC is disproportionate when the change is already identified; its strength is finding causes nobody has isolated. Option 3 fails because FMEA is a prospective tool for a process being designed or redesigned, and no new process is being built. Option 4 fails on scope: a value-stream map answers questions about flow across departments, not about one prompt on one ward.
Question 2: choosing the tool
An improvement team has an aim to reduce unplanned readmissions and has generated eleven possible interventions. Members disagree about which would matter most, and no shared explanation of why readmissions occur has been written down. What should the team do next?
- Build a driver diagram linking the aim to primary drivers and change ideas
- Plot the last twelve months of readmissions on a control chart
- Rank the eleven interventions by effort and impact and start with the easiest
- Conduct a root cause analysis of the three most recent readmissions
Answer: 1. The gap is an absent theory of change, and a driver diagram exists to make that theory explicit so interventions attach to the drivers they are meant to move. Option 2 is reasonable to have done already, but a control chart describes the behaviour of the measure and will not settle a disagreement about causes. Option 3 prioritises effort over logic, which is how teams end up with eleven small changes and no movement. Option 4 applies a retrospective event-analysis method to a chronic gap, and three cases will not represent the pattern.
Question 3: holding the gain
A surgical unit reduced its case cancellation rate substantially during a project that ended nine months ago. The rate has returned to its previous level. The changes were never written into the unit's standard procedures, and the project lead has moved department. What is the most appropriate action?
- Repeat staff education on the cancellation process
- Establish a control plan with standard work, a named owner and the measure in routine unit reporting
- Begin spreading the original changes to the other surgical units
- Escalate the deterioration to the quality committee for review
Answer: 2. The stem hands you the diagnosis: no standard work, no owner, no ongoing measurement. That is a sustainability failure, and the response is the infrastructure that was missing. Option 1 is the reflex answer and the weakest form of action: education does not survive turnover and was not what failed. Option 3 spreads an unstable process. Option 4 reports the deterioration without correcting it. When two options look defensible, choose the one that changes the system rather than the one that informs somebody.
How this domain connects to the ones either side of it
Performance improvement sits directly against health data analytics, which carries 26 scored items. The overlap is the measurement half of every project: run charts, control charts, common and special cause variation, operational definitions and sampling. This domain asks what you should do; analytics asks whether what you did changed anything. Items that show a chart and ask about the signal belong to analytics; items that show a chart and ask what the team should do next belong here.
On the other side sits patient safety with 18 scored items, sharing the cause-analysis toolkit but triggered by harm rather than a performance gap. Quality leadership takes over whenever the obstacle in a stem is a person or a committee rather than a process.
A ten-point revision checklist for this domain
- State the weighting from memory: 27 of 125 scored items, 21.6 per cent, the largest single domain.
- Write the three questions of the Model for Improvement without looking, and explain why a PDSA cycle is for learning rather than for proving.
- List the five DMAIC phases and say in one sentence what the Control phase delivers.
- Name the eight wastes with a hospital example of each from another department.
- Distinguish a process map, a value-stream map and a workflow diagram by what each records.
- Draw a driver diagram for a familiar aim, with two primary drivers and a change idea under each.
- Explain when a fishbone belongs in improvement and when the same tool belongs in patient safety.
- Describe what a control plan contains, and why education alone is a weak sustainability action.
- Explain the difference between spread and sustainability, and what each requires.
- Practise ten method-selection items and, for each wrong answer, name the cue you missed.
What to do next
Work through method-selection items until you can name the deciding cue before you read the options; that habit is worth more marks here than extra reading. The companion lesson, with the mapping tools drawn out step by step, sits in the CPHQ study video library, and the free CPHQ practice test will show where this domain currently stands. The primary source for the weighting is NAHQ's CPHQ credential page.
