The Six Sigma expert uses qualitative and quantitative techniques to drive process improvement. Although the tools, themselves, are not unique, the way they are applied and integrated as part of a system is.
Six Sigma professionals do not always agree as to exactly which tools constitute the set. Some of the statistical and graphical tools commonly used in improvement projects are listed below.
Defining a problem, improvement opportunity, or requirements:
Project charter to define the focus, scope, direction, and motivation for the improvement team
Voice of the customer to understand feedback from current and future customers indicating offerings that satisfy, delight, and dissatisfy them
Value stream map to provide an overview of an entire process, starting and finishing at the customer, and analyzing what is required to meet customer needs
Measuring process performance:
Process map for recording the activities performed as part of a process
Capability analysis to assess the ability of a process to meet specifications
Pareto chart to analyze the frequency of problems or causes
Analyzing processes to determine root causes of variation, defects, or poor performance:
Root cause analysis to uncover causes
Failure mode and effects analysis for identifying possible product, service, and process failures
Multi-vari chart to detect different types of variation within a process
Improving process performance by addressing root causes:
Design of experiments (DOE) to solve problems from complex processes or systems where there are many factors influencing the outcome and where it is impossible to isolate one factor or variable from the others
Kaizen event to introduce rapid change by focusing on a narrow project and using the ideas and motivation of the people who do the work
Controlling the improved process and future performance:
Control plan to document what is needed to keep an improved process at its current level
Statistical process control (SPC) for monitoring process behavior
5S to create a workplace suited for visual control
Mistake proofing (poka-yoke) to make errors impossible or immediately detectable
Additionally, Six Sigma team leaders often use project management tools such as Gantt charts and team engagement tools like brainstorming and nominal group technique.