Statistical Process Control

Overview

1. Definition of Statistical Process Control

2. Common causes and assignable causes of variation

3. Control charts

4. Type I and Type II Errors

5. R, x, p, and c charts

6. Process Distribution

Definition of SPC

Statistical process control (SPC) is the application of statistical techniques to determine whether the output of a process conforms to the product or service design.

Common causes of variation

Process Distribution for the Box-Filling Machine When Only Common Causes of Variation Are Present

Assignable causes of variation

Effects of Assignable Causes

Control Charts - Examples

Type I and Type II Errors

R-chart

A range chart, or R-chart, is used to monitor process variability.

x-ChartsAn x-chart (read " x-bar chart") is used to measure the mean.

p-ChartsThe p-chart is a commonly used control chart for attributes.

c-ChartsWhen management is interested in reducing the number of defects per unit, another type of control chart, the c-chart, is useful.

Process Distribution

Conclusion

1. Definition of Statistical Process Control

2. Common causes and assignable causes of variation

3. Control charts

4. Type I and Type II Errors

5. R, x, p, and c charts

6. Process Distribution

= Quality Control and Lower Costs