CQI Statistical Process Control Flashcards

What is acceptance sampling used for in quality control?

Answer: To make accept/reject decisions about a lot based on inspection of a random sample

Acceptance sampling uses statistical rules to decide whether to accept or reject an entire lot based on the inspection results of a random sample drawn from it.

What does AQL (Acceptable Quality Level) represent?

Answer: The maximum percentage of defectives considered satisfactory as a process average for acceptance sampling

AQL is the maximum defect rate that is considered satisfactory as a process average, defining the quality level at which the sampling plan provides a high probability of acceptance per ANSI/ASQ Z1.4.

What is the difference between Type I and Type II errors in acceptance sampling?

Answer: Type I rejects good lots (producer's risk); Type II accepts bad lots (consumer's risk)

Type I error (producer's risk/alpha) occurs when a good lot is rejected; Type II error (consumer's risk/beta) occurs when a bad lot is accepted.

What is the primary US standard used for attribute acceptance sampling plans?

Answer: ANSI/ASQ Z1.4

ANSI/ASQ Z1.4 (formerly MIL-STD-105) is the primary US standard for acceptance inspection by attributes, widely used across manufacturing industries.

In SPC, what does 'voice of the process' (VOP) refer to?

Answer: The natural variation of a process as expressed through control limits

Voice of the Process (VOP) refers to the natural process variation expressed through control limits, as opposed to the Voice of the Customer (VOC) expressed through specification limits.

What is a histogram used for in quality analysis?

Answer: To display the frequency distribution of a data set and visualize process variation

A histogram displays the frequency distribution of a dataset, helping quality professionals visualize the shape, center, and spread of process variation.