Are crucial to the success of any new product or service because they the product gain market acceptance by spreading positive word of mouth about the new product.

Statistical process control charts: a. indicate to the operator the true quality of material leaving the process. b. display upper and lower limits for process variables or attributes and signal when a process is no longer in control. c. indicate to the process operator the average outgoing quality of each lot. d. display the measurements on every item being produced. e. are a graphic way of classifying problems by their level of importance, often referred to as the 80-20 rule.