Six sigma or design for six sigma?

Six sigma has been considered as a philosophy that employs a well-structured continuous improvement methodology to reduce process variability and drive out waste within the business processes using statistical tools and techniques (Bañuelas and Antony, 2002). The main focus of six sigma is to reduce potential variability from processes and products by using either a continuous improvement methodology or a design/redesign approach known as design for six sigma (DFSS). The former follows the phases: define, measure, analyse, improve and control. This approach is known as DMAIC methodology and is employed in existing processes/products. On the other hand, design...