| assignable variation | a variation whose cause can be identified.
|
 |
|
|
| attribute | a characteristic that has just two choices, e.g., defective or acceptable.
|
|
|
|
| c-chart | for a continuous process, a type of control chart based on the number of defects per unit.
|
|
|
|
| conformance | the characteristics of the product satisfy the established standard for the characteristics.
|
|
|
|
| control chart | a technique devised by Walter Shewhart to monitor the quality level of work in process.
|
|
|
|
| control limit | see upper control limit and lower control limit.
|
|
|
|
| inspection | examining material in process or finished products to determine conformance to standard.
|
|
|
|
| liability | the legal responsibility of a producer for defects of a product or service that causes injury, harm, or property damage.
|
|
|
|
| lower control limit (LCL) | in a Shewhart-type control chart, the lower limit of the random scatter of a sample statistic, to define whether a process is in control or out of control.
|
|
|
|
| p-chart | for attribute process control, a type of control chart based on the proportion of defective items in a sample.
|
|
|
|
| process capability | the variation allowed by the design specification relative to the inherent variability of process output.
|
|
|
|
| process capability ratio | a measure of the capability of the manufacturing process to meet the specifications of the product. It is the ratio of the specification width to the process width.
|
|
|
|
| process control | automated computer-controlled operations in a production process; for example, a chemical plant refinery.
|
|
|
|
| quality control | a process that measures output relative to a standard and acts when the output does not meet the standards.
|
|
|
|
| quality of conformance | a product or service conforms to specifications.
|
|
|
|
| random variation | natural variations in the output of a processes, created by countless minor factors.
|
|
|
|
| range (R) | the range of values of the observations in a sample.
|
|
|
|
| range chart | a control chart for variation in the ranges of output samples.
|
|
|
|
| run | a sequence of observations with a certain characteristic.
|
|
|
|
| run test | a test for randomness.
|
|
|
|
| statistical process control | statistical evaluation of the output of a process during production.
|
|
|
|
| tolerances | specifications for the range of acceptable values of the measurements of a product established by engineering design or customer requirements.
|
|
|
|
| type I error | incorrectly concluding a process is out of control.
|
|
|
|
| Type II error | incorrectly concluding a process is in control.
|
|
|
|
| upper control limit (UCL) | in a Shewhart-type control chart, the upper limit of the random scatter of a sample statistic, to define whether a process is in control or out of control.
|
|
|
|
| variable | a measurable characteristic on a continuous scale, such as height, weight, pressure, speed, etc.
|
|
|
|
| x-bar chart | a type of control chart for variables, based on the mean and standard deviation of a sample.
|