Six Sigma Tools (Analyze)

Question 1

Root cause analysis - current reality tree (CRT)

Answer 1

• A tool that helps list observed problems and link them to causes
• How:
  (1) Determine the scope of the analysis;
  (2) List between 5-10 undesirable effects (UDEs) based on observation;
  (3) Diagram the cause and effect relationship between different entities.

Question 2

Root cause analysis - 5 Whys

Answer 2

• Keep asking whys
• Especially helpful in case of human error
• Although this technique is called “5 Whys,” you may find that you will need to ask the question fewer or more times than five before you find the issue related to a problem.

Question 3

Root cause analysis - Fishbone

Answer 3

• Aka Cause–and–Effect Diagram, Ishikawa Diagram
• Identify many possible causes for an effect or problem.
• It can be used to structure a brainstorming session. It immediately sorts ideas into useful categories.
• How:
• Agree on a problem statement (effect)
• Brainstorm the major categories of causes of the problem (e.g. referencing 6M)
• Brainstorm all the possible causes of the problem

Question 4

KJ/Affinity Diagrams

Answer 4

• Brainstorming tool (also used in the define stage)

Question 5

Spaghetti diagram

Answer 5

• Aka workflow mapping
• Purpose: Highlight inefficiencies in the workflow and/or layout of a process.
• How:
• Map the actual path of a part, material or resource (i.e. a worker) along the shop-floor
• -Estimate and minimize (1) Total distance travelled, and (2) Number of times an item is handled

Question 6

Failure Modes and Effects Analysis (FMEA)

Answer 6

• A quality improvement method that enables the identification and prevention of errors before they occur
• A semi- quantitative approach designed to identify ways in which a process can fail to meet customer requirement
• Prioritization process, focusing on actions that should be taken to rectify an error
• Rate the severity (S) of a failure effect on the customers, rank the probability of occurrence (O) of a failure, and rank the probability of detection (D), and then calculate the Risk Priority Number (RPN = S * O * D).

Question 7

Business Impact Analysis (BIA)

Answer 7

• A formal analysis of the effect on the business if a specific process fails or loses efficiency
• Identify the minimum performance level of a given process that an organization requires to continue operating.

Question 8

Pareto Analysis

Answer 8

• A pareto chart is a bar graph that depicts the significance of factors by arranging the longest bar on the left and shortest to the right in descending order. - When to use it: (a) when analyzing data about the frequency of problems or causes in a process; (b) when there are many problems or causes and you want to focus on the most significant; (c) when analyzing broad causes by looking at their specific components; (d) when communicating with others about your data.