Lean and Six Sigma are documented approaches to business analysis. Lean focuses on maximizing value by eliminating waste and optimizing processes, thereby improving overall efficiency. Six Sigma is a methodology that seeks to improve the quality of process outputs by identifying and removing the causes of defects and minimizing variability. The Waterfall approach, while primarily a project management methodology that uses a sequential design process, can also be used in certain business analysis contexts. Deming's Quality Circle, which involves the cycle of plan, do, check, and act, is more associated with quality management rather than a specific approach to business analysis.