Maintaining the calibration of an information system

The design and operation of an information system requires assumptions on the values of parameters which characterize the behavior of pertinent random processes. If these parameters remain constant over time at design values, system performance will be as specified. Otherwise, performance will vary from design and cost and service penalties will arise. A control chart procedure is introduced for monitoring system parameters and introducing appropriate action to reset them to design values as indicated. The control system is set so that the expected cost of monitoring is a minimum. A table of control system settings over a broad set of a priori assumptions is provided. Examples describing the procedure and use of the table are given.