SPC Data Collection & Interpretation 5

Question 1

Which formula correctly calculates the mean (Xbar) of a subgroup with values 8, 10, 12, and 14?

Accepted Answer

(8+10+12+14) / 4 = 11

Answer

(8+14) / 2 = 11

Answer

14 - 8 = 6

Answer

(8×10×12×14)^0.25

Question 2

A quality team notices that data from one shift consistently shows higher average values. This is BEST addressed by:

Accepted Answer

Stratifying data by shift and investigating the shift-specific cause

Answer

Ignoring the pattern if all points are within control limits

Answer

Widening the control limits to accommodate shift differences

Answer

Reducing sample frequency on that shift

Question 3

In SPC data collection, a sampling plan that selects every nth unit is called:

Accepted Answer

Systematic sampling

Answer

Stratified sampling

Answer

Cluster sampling

Answer

Judgment sampling

Question 4

Which statistic measures the spread of individual measurements within a subgroup on an Xbar-R chart?

Accepted Answer

Range (R)

Answer

Subgroup mean (Xbar)

Answer

Grand mean (Xdoublebar)

Answer

Process capability index (Cp)

Question 5

When a process is described as 'in statistical control,' it means:

Accepted Answer

Only common cause variation is present and the process is stable and predictable

Answer

All output meets specification requirements

Answer

The process Cp is greater than 1.33

Answer

No defects are being produced

Question 6

A quality engineer discovers that measurement data has a uniform distribution rather than the expected bell shape. This may indicate:

Accepted Answer

Data from multiple machines or operators has been pooled without stratification

Answer

The process is perfectly capable

Answer

The control chart is not needed

Answer

Sample sizes are too large

Question 7

Which of the following actions BEST ensures data integrity during SPC data collection?

Accepted Answer

Defining clear operationally defined measurement procedures and training all collectors

Answer

Using the largest possible sample size regardless of cost

Answer

Collecting data only when the process appears to be running poorly

Answer

Allowing inspectors to round values to whole numbers for simplicity