CPHQ Statistical Process Control 5

Question 1

A neonatal ICU tracks central-line-associated bloodstream infections (CLABSIs) per 1,000 line-days. The monthly line-days vary. Which chart is most appropriate?

Accepted Answer

u-chart

Answer

np-chart

Answer

c-chart

Answer

p-chart

Question 2

A Shewhart control chart uses 3-sigma limits. What probability of a false alarm does this correspond to for normally distributed data?

Accepted Answer

0.27%

Answer

5.0%

Answer

2.5%

Answer

1.0%

Question 3

When should a healthcare team recalculate control chart limits?

Accepted Answer

After a confirmed, sustained process change or improvement

Answer

Every month regardless of process changes

Answer

Whenever a point falls outside control limits

Answer

When the sample size changes by one unit

Question 4

A quality analyst is choosing between an X-bar & R chart and an X-bar & S chart for monitoring blood glucose turnaround times with subgroup size n=12. Which should she choose and why?

Accepted Answer

X-bar & S, because the S chart is more efficient for subgroup sizes larger than about 8–10

Answer

X-bar & R, because ranges are always more accurate for large samples

Answer

X-bar & R, because ranges are easier to compute than standard deviations

Answer

X-bar & S, because S charts work only for subgroup sizes above 10

Question 5

A hospital's patient fall rate has been stable for 18 months. Administration mandates a new rounding protocol. After implementation, five consecutive months show rates below the previous centerline. What is the appropriate SPC action?

Accepted Answer

Declare a special cause signal and investigate the improvement

Answer

Widen control limits to include the new lower values

Answer

Continue monitoring without any chart modification

Answer

Remove the five outlier months from the baseline

Question 6

In SPC terminology, a process is said to be 'in statistical control' when:

Accepted Answer

Only common cause variation is present and no control chart rules are violated

Answer

All outputs meet customer specification limits

Answer

The Cpk value exceeds 1.33

Answer

The process average equals the target value

Question 7

Which action is appropriate when special cause variation is identified on a healthcare control chart?

Accepted Answer

Identify and eliminate the root cause of the special cause

Answer

Adjust the process mean to the centerline immediately

Answer

Increase sample size to reduce false alarms

Answer

Recalculate control limits using tighter sigma values