The most important benefit of Statistical process control (SPC) is its ability to let the manufacturer accurately determine what is happening to the process on a real-time basis. Since SPC functions on the principle of controlling the process to prevent defects in the product, it is crucial that the process be understood, measured, and controlled by manufacturing personnel. Any processes that have characteristics that can be measured using variable data are candidates for statistical process control. This includes processes that alter the product’s dimensions, electrical conductivity, weight, and so forth. Operators who take and record data need to be trained how to perform this task without introducing errors or bias. Operator and inspector certification programs are indispensable for employee training. These programs define the basic skills and knowledge to be accomplished by the training program. Information regarding the programs can be obtained from industry publications.