1. Assignable Variation Defined
2. Common Variation Defined
   
   
1. Variation Around Us
   1. Upper and Lower Specification or Tolerance Limits Defined
      
      
2. Process Capability
   1. Six-Sigma Defined
   1. Capability Index Defined
      1. Capability Index (C_pk)
         
         
3. Process Control Procedures
   1. Statistical Process Control (SPC) Defined
   2. Attributes Defined
   1. Process Control With Attribute Measurement: Using p Charts
   2. Process Control With Variable Measurement: Using X-bar and R Charts
      1. Variables Defined
   3. How to Construct X-bar and R Charts
      
      
4. Acceptance Sampling
   1. Design of a Single Sampling Plan for Attributes
   2. Operating Characteristic Curves
      
      
5. Conclusion

This technical note on statistical quality control (SQC) covers the quantitative aspects of quality management. Statistical quality control includes acceptance sampling and process control. Acceptance sampling involves testing a random sample of existing goods and deciding whether to accept an entire lot based on the quality of the random sample. Statistical process control involves testing a random sample of output from a process to determine whether the process is producing items within a prespecified range. The techniques presented in this chapter are used to ensure quality control of processes and output. Key points to consider are the costs to justify inspection as well as the correct sampling plan to ensure quality. While there are variations in every process, as variation is reduced, quality is improved.

Process control monitors quality while the product or service is being produced. Techniques for measurement of process control as well as charting procedures are presented along with a discussion of size of samples, number of samples, frequency of sampling, and control limits. Motorola made process capability famous by adopting its well-known six-sigma quality limits, ensuring only 3.4 defects per million using six-sigma quality limits.