Noise factors are disturbances that cause the systems response to shift from specification. These factors are likely beyond the designer's control, such as manufacturing tolerances, aging, usage patterns, environmental conditions, etc. Noise factors must be identified and quantified so that accurate choices can be made about which effects require compensation. Control factors are used by the designer to compensate for noise factors that could significantly influence the system away from nominal performance.
Once the critical noise factors are identified and the control factors selected, a Robust Design flow is used to implement and analyze the design to ensure system reliability. The objective of a Robust Design flow is to meet performance requirements with the highest possible system reliability and the most reasonable systems cost.