Principle 23. Feedback

1. Introduce feedback (referring back, cross-checking) to improve a process or action.
   Automatic volume control in audio circuits
   Signal from gyrocompass is used to control simple aircraft autopilots.
   Statistical Process Control (SPC) -- Measurements are used to decide when to modify a process. (Not all feedback systems are automated!)
   Budgets --Measurements are used to decide when to modify a process.
2. If feedback is already used, change its magnitude or influence.
   Change sensitivity of an autopilot when within 5 miles of an airport.
   Change sensitivity of a thermostat when cooling vs. heating, since it uses energy less efficiently when cooling.
   Change a management measure from budget variance to customer satisfaction.