Quality of design refers to the characteristics that designers specify for an item. The grade of materials, tolerance, and performance specifications all contribute to quality of design. As higher graded materials are used and tighter, tolerance and greater levels of performance are specified the design quality of a product increases if the product is manufactured according to specifications.
Quality of conformance is the degree to which the design specifications are followed during manufacturing. Again, the greater the degree of conformance, the higher the level of quality of conformance.
In software development, quality of design encompasses requirements, specifications and design of the system.
Quality of conformance is an issue of focused primarily on implementation. If the implementation follows the design and the resulting system meets its requirements and performance goals, conformance quality is high.
QC is the series of inspections, reviews, and tests used throughout the development cycle to ensure that each work product meets the requirements placed upon it. QC includes a feedback loop to the process that created the work product. The combination of measurement and feedback allows us to tune the process when the work products created fail to meet their specification. These approach views QC as part of the manufacturing process QC activities may be fully automated, manual or a
combination of automated tools and human interaction. An essential concept of QC is that all work products have defined and measurable specification to which we may compare the outputs of each process the feedback loop is essential to minimize the defect produced.
QA consists of the editing and reporting functions of management. The goal of quality assurance is to provide management with the data necessary to be informed about product quality, there by gaining insight and confidence that product quality is meeting its goals. Of course, if the data provided through QA identify problems, it is management's responsibility to address the problems and apply the necessary resources to resolve quality issues.