A hospital's central line-associated bloodstream infection (CLABSI) rate has
12 data points with one point above the upper control limit and a run of 8
points below the centerline. According to Shewhart and Western Electric rules,
what is the most appropriate interpretation?
A. Both signals indicate special cause variation; investigate the single
outlier and the sustained shift separately.
B. The single outlier is special cause, but the run of 8 below the centerline
is common cause because it reflects improvement.
C. Only the run of 8 is significant; the single outlier should be ignored as
random noise.
D. Neither signal is actionable until 20 data points are available for
baseline stability.
Correct Answer: A - Both signals indicate special cause variation;
investigate the single outlier and the sustained shift separately.
RATIONALE
Western Electric rules flag both a point beyond the control limit and a
run of 8 on one side of the centerline as special cause signals, each
requiring separate investigation. Option B incorrectly dismisses a
sustained shift as common cause, and C ignores the outlier. D is
wrong because 12 points can already reveal special cause patterns;
waiting for 20 would delay action.
Question 2
A multidisciplinary team is chartering a Six Sigma project to reduce
medication reconciliation errors. Which project charter element most directly
ensures the project remains aligned with organizational strategy and avoids
scope creep?
A. A detailed Gantt chart with task dependencies
B. A problem statement with baseline data and a goal statement tied to
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, strategic priorities
C. A list of all possible root causes from a fishbone diagram
D. A RACI matrix assigning every team member to tasks
Correct Answer: B - A problem statement with baseline data and
a goal statement tied to strategic priorities
RATIONALE
The problem and goal statements in a charter link the project to
strategic objectives and define boundaries, which prevents scope
creep. A Gantt chart and RACI matrix are execution tools, not
alignment tools. A fishbone list is exploratory and can expand scope
rather than constrain it.
Question 3
During a value stream mapping exercise for an outpatient clinic, the team
identifies that 70% of total patient time is waiting between steps. Which Lean
concept best characterizes this finding and its primary implication?
A. Muda (waste); the focus should be on eliminating non-value-added
waiting to improve flow.
B. Mura (unevenness); the focus should be on leveling demand to reduce
waiting.
C. Muri (overburden); the focus should be on reducing staff workload to
speed up steps.
D. Poka-yoke (error-proofing); the focus should be on preventing
scheduling mistakes.
Correct Answer: A - Muda (waste); the focus should be on
eliminating non-value-added waiting to improve flow.
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, RATIONALE
Waiting is a classic form of muda (non-value-added waste), and value
stream mapping quantifies it to target flow improvements. Mura refers
to unevenness in workload or demand, not the waiting itself. Muri is
overburden on people or equipment, and poka-yoke is error
prevention, neither of which directly addresses the 70% waiting
finding.
Question 4
A quality improvement team wants to test a new sepsis screening protocol.
They plan to implement it on one unit for two weeks, study the results, and
then decide whether to adapt, adopt, or abandon. Which improvement
framework does this describe?
A. DMAIC
B. PDSA
C. FMEA
D. HRO
Correct Answer: B - PDSA
RATIONALE
The Plan-Do-Study-Act (PDSA) cycle is designed for small-scale,
rapid tests of change with iterative learning. DMAIC is a structured
Six Sigma project methodology, FMEA is a proactive risk assessment,
and HRO is an organizational safety culture framework, none of which
describe this iterative test-and-learn cycle.
Question 5
A process has a Cp of 1.5 and a Cpk of 0.8. What is the most accurate
interpretation of this discrepancy?
A. The process is highly capable and centered; no action is needed.
B. The process spread is acceptable, but it is not centered within
specification limits, so centering is needed.
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