How does Six Sigma define 'Defect'?

In Six Sigma, a 'Defect' is defined as an error in the process that causes customer dissatisfaction. This understanding is rooted in the primary objective of Six Sigma, which is to meet and exceed customer expectations. When a defect occurs, it indicates that a product or service fails to fulfill the requirements or standards that the customer anticipates, leading to dissatisfaction.

This definition emphasizes the importance of the customer’s perspective in evaluating quality. A defect is not merely a technical shortfall but is fundamentally linked to how a product or service is perceived by the customer. If the expected quality, functionality, or experience does not meet the customer's requirements, it is labeled as a defect. This concept is crucial in Six Sigma methodologies, which aim to identify and minimize defects in processes to improve overall quality and customer satisfaction.

The other definitions, while related to aspects of process and performance, do not align with the specific focus of Six Sigma on customer dissatisfaction as a direct measure of quality. Options such as delays in project completion or variances in expected outcomes, while relevant to project management and process control, do not address the customer-centric understanding of what constitutes a defect in Six Sigma.