A further component of the transformation model in Figure 1 is the feedback loop. Feedback information is used to control the operations system, by adjusting the inputs and transformation processes that are used to achieve desired outputs. For example, a chef relies on a flow of information from the customer, through the waiter, about the quality of the food. Adverse feedback might lead the chef to change the inputs (for example by buying better quality potatoes) or the transformation process (for example by changing the recipe or the cooking method).
Feedback is essential for operations managers. It can come from both internal and external sources. Internal sources include testing, evaluation and continuously improving goods and services; external sources include those who supply products or services to end-customers as well as feedback from customers themselves.