Statistics Quality Control & Assurance 2

Question 1

In a p-chart used for attribute data, what does 'p' represent?

Accepted Answer

The proportion of defective items in a sample

Answer

In a p-chart, p represents the proportion (fraction) of nonconforming or defective items found in each sample.

Question 2

Which type of variation in a process is also called 'common cause' variation?

Accepted Answer

Random variation

Answer

Random (common cause) variation is inherent to the process and results from many small, unavoidable sources, unlike assignable (special) cause variation.

Question 3

A manufacturer wants to estimate the minimum sample size to detect a 1.5-sigma shift in the process mean with 80% power using an X-bar chart. Which factor does NOT directly affect this calculation?

Accepted Answer

The supplier's lead time

Answer

Supplier lead time is a logistics factor and has no role in the statistical power calculation for control chart sample size.

Question 4

What is the purpose of a gage R&R (Repeatability and Reproducibility) study?

Accepted Answer

To quantify how much of total variation is due to the measurement system

Answer

A gage R&R study partitions total observed variation into product variation versus measurement system variation (repeatability + reproducibility).

Question 5

On a control chart, a run of 8 consecutive points on the same side of the center line indicates:

Accepted Answer

A possible process shift requiring investigation

Answer

Eight consecutive points on one side of the center line is a non-random pattern (Western Electric Rule) signaling a probable process shift.

Statistics Practice Test

Statistics Practice Test

Statistics Quality Control & Assurance 2