Quality Assurance & Improvement Flashcards

The Deming Cycle (PDCA) in quality improvement stands for:

Answer: Plan, Do, Check, Act

PDCA stands for Plan, Do, Check, Act — a four-step iterative improvement cycle attributed to W. Edwards Deming.

In process control, a Type II error (beta risk) in hypothesis testing refers to:

Answer: Failing to detect a real shift in the process mean

A Type II error (beta risk) occurs when a statistical test fails to detect a real process change that has actually occurred.

An automation engineer wants to reduce measurement variability in a temperature control loop. Which action directly improves measurement system repeatability?

Answer: Replacing the sensor with a higher-precision instrument

Repeatability is the gauge's inherent variability under identical conditions; replacing the sensor with a more precise one directly reduces this variation.

Which of the following is a key characteristic of attribute data in quality control?

Answer: Classified into discrete categories such as pass/fail or defect counts

Attribute data categorizes items into discrete groups (e.g., conforming/nonconforming) rather than measuring them on a continuous scale.

What is the main difference between a defect and a defective unit in quality terminology?

Answer: A defective unit has one or more defects; a defect is a single nonconformance on any unit

A defect is a single nonconformance, while a defective unit is any unit containing one or more defects and is therefore nonconforming.

In Six Sigma, what sigma level corresponds approximately to 3.4 DPMO (defects per million opportunities)?

Answer: Six sigma

Six Sigma quality corresponds to approximately 3.4 DPMO, accounting for a 1.5-sigma long-term process shift from the nominal.

A control chart for fraction nonconforming with variable subgroup sizes should use which chart type?

Answer: p-chart

The p-chart tracks the fraction (proportion) nonconforming and accommodates varying subgroup sizes, making it suitable for variable sample sizes.