Chapter 10 Quality Control

Key terms

Inspection- appraisal of goods or services

Quality of conformance- a product or service conforms to specifications

Statistical process control- statistical evaluation of the output of a process during production

Random variation- natural variation in the output of a process, created by countless minor factors

Assignable variation- in process output, a variation whose cause can be identified

Control chart- a time-ordered plot of sample statistics, used to distinguish between random and nonrandom variability

Control limits- the dividing lines between random and nonrandom deviations from the mean of the distribution

Type I error- concluding a process is not in control when it actually is

Type II error- concluding a process is in control when it is not

Variables- generate data that are measured

Attributes- generate data that are counted

Mean control chart- control chart used to monitor the central tendency of a process

Range control chart- control chart used to monitor process dispersion

p-chart- control chart for attributes, used to monitor the proportion of defective items in a process

c-chart- control chart for attributes, used to monitor the number of defects per unit

Run test- a test for randomness

Run- sequence of observations with a certain characteristic

Specifications- a range of acceptable values established by engineering design or customer requirements

Process variability- natural or inherent variability in a process

Process capability- the inherent variability of process output relative to the variation allowed by the design specification