> - model the concept system, such that the closed loop transfer functions can be determined
> - Identify all significant disturbances.
> Model them with their _Power Spectral Density_
> - Define the performance outputs of the system and simulate the output error.
> Using the theory of _propagation_, the contribution of each disturbance to the output error can be analyzed and the critical disturbance can be pointed out
> - Make changes to the system that are expected to improve the performance level, and simulate the output error again.