Although eXpress analyses can be used to assess the diagnostic capability of a fixed system design, eXpress really comes into its own when the results are used to improve a design’s diagnostic capability. Unlike spreadsheet-based approaches, eXpress has been specifically designed to facilitate both early and iterative analysis; in fact, it can be effectively employed throughout the product development cycle, beginning in the earliest phases of system design. The value of this early design feedback cannot be over-estimated—if diagnostic analysis is postponed until later phases of the design process, it becomes much less cost-effective to implement the recommended changes. Additional costs can result not only from duplicated effort as the design is re-engineered, but also from situations where existing funds have already been allocated and therefore “new” funds must be found for the design changes. Unfortunately, when postponed analyses provide unattractive assessments of a system’s diagnostic capability, there is a temptation either to sweep the results under the metaphorical rug or to somehow develop positive “spin” on the “negative” numbers.