Statistical quality control refers to the use of statistical methods in the monitoring and maintaining of the quality of products and services one method referred to as acceptance sampling can be used when a decision must be made to accept or reject. Statistical quality control sqc is the application of statistical methods for the purpose of determining if a given component of production input is within acceptable statistical limits and if there is some result of production output that may be shown to be statistically acceptable to required specifications 688. Statistical quality control sqc is defined as the application of the 14 statistical and analytical tools 7 qc and 7 supp to monitor process outputs dependent variables statistical process control spc is the application of the same 14 tools to control process inputs independent variables although both terms are often used interchangeably sqc includes acceptance sampling where spc does not. Statistical quality control refers to the technique of ascertaining whether the variation in the quality of the product is due to chance causes or due to assignable causes if the variation is due to assignable causes it is detected and some corrective action is planned to improve the quality of the product