Question: Dave’s Restaurant is a chain that employs independent evaluators to visit its restaurants as customers and assess the quality of the service by filling out a questionnaire. The company evaluates restaurants in two categories, products (the food) and service (e.g., promptness, order accuracy, courtesy, friendliness). The evaluator considers not only her order experiences but also observations throughout the restaurant. Following are the results of an evaluator’s 20 visits to one particular restaurant during a month showing the number of “defects” noted in the service category:

Choose an appropriate type of control chart to use in this instance. Compute the 3 \(\sigma \) control limits for this control chart, draw the control chart, and indicate whether or not the process is in control.