CQE Statistical Process Control 2

Question 1

Which type of variation is inherent to a stable process and cannot be eliminated without changing the process itself?

Accepted Answer

Common cause variation

Answer

Common cause variation is the natural, random variation built into the process design, and reducing it requires fundamental process changes rather than firefighting.

Question 2

What does an OC (Operating Characteristic) curve display in acceptance sampling?

Accepted Answer

The probability of accepting a lot at various quality levels

Answer

An OC curve plots the probability of lot acceptance against the actual incoming lot quality (fraction defective), helping evaluate sampling plan performance.

Question 3

In SPC, a 'run of 8 consecutive points on one side of the centerline' is an example of:

Accepted Answer

A signal of special cause variation

Answer

Eight consecutive points on one side of the centerline is a classic run rule that signals a process shift or special cause, as the probability of this occurring by chance is very low.

Question 4

Short-term process capability is typically measured using data collected over what period?

Accepted Answer

A single brief study period under stable conditions

Answer

Short-term capability (Cp/Cpk) is measured during a controlled study with minimal time-to-time variation, representing the best the process can achieve.

Question 5

What statistical distribution is typically assumed for attribute control charts such as the p-chart?

Accepted Answer

Binomial distribution

Answer

The p-chart is based on the binomial distribution, which models the probability of a certain number of nonconforming items in a sample when each item is independently classified as pass or fail.

CQE - Certified Quality Engineer Practice Test

CQE - Certified Quality Engineer Practice Test

CQE Statistical Process Control 2