Abstract: Apparatus for optimising the design of a manufacturing process in order to achieve predetermined goals including: A computer simulation model of the structural elements of a manufacturing process pre-programmed to operate according to predetermined flow and sequencing rules and data describing the required product mix and to output, during operation, data on request relating to breakdowns and queues at various resources within the process. A calculator received the data and calculates first values of complexity and constituent elements thereof from the output data of the computer simulation model and second values of complexity and constituent elements thereof from similar data relating to the real manufacturing process in operation.