Six Sigma | Chapter 7 - DMAIC, Analyze Flashcards
In DMAIC, for Analyze, what are the Inputs of the methodology?
- Well-Defined Processes
- Baseline Process Capabilities
- Process parameters affecting CTQ
- Cost of Poor Quality (COPQ)
- Measurement Systems
In DMAIC, for Analyze, what are the Outputs of the methodology?
- Important Causes of Defects
- Special and Common Causes of Variation
- DPMO and Sigma Level
In DMAIC, for Analyze, what are the Tools of the methodology?
- Ishikawa Diagrams
- Failure Mode & Effects Analysis
- Hypothesis Testing
- Process Capability Study
In DMAIC, for Analyze, within Tools who developed the Ishikawa Diagrams and when?
Developed by Kaoru Ishikawa in 1960’s
In DMAIC, for Analyze, what are the objectives of the analyze phase?
In Analyze phase, our objectives are:
- Doing analysis of present system
- Analyzing whether the present system can be further improved
- Determining the failure points for the proposed changes
- Determining major milestones and risks in successfully completing the project
- Analyzing how the process capability would improve if suggested changes are made.
In DMAIC, for Analyze, within Tools what are other names for Ishikawa Diagrams?
Ishikawa diagrams are also referred to as cause-and-effect or Fishbone diagram
In DMAIC, for Analyze, within Tools what does the Ishikawa Diagrams represent?
This is a graphic representation of possible causes for any particular problem under study.
In DMAIC, for Analyze, within Tools what are the benefits of Ishikawa Diagrams?
Benefits of Ishikawa diagram
- Usually created by a group of people who have knowledge of the process and understand the problems in the present system.
- Is a very powerful tool to organize and graphically display all the knowledge the team has about a particular problem
- Clarifies the understanding the team has regarding the process. If an Ishikawa diagram does not show appropriate level of detail, it indicates that the team has a superficial knowledge of the problem. Hence, additional study of the system or involvement of Subject Matter Experts is required.
- Is a starting point to determine the Vital X’s that impact the customer’s critical to quality variable : Y. (Details about Y and Vital X’s as defined in the chapter 2: Stakeholders, customers and financial measures)
In DMAIC, for Analyze, within Tools what are the steps to create Ishikawa Diagrams?
Steps involved in creation of Ishikawa diagram:
- Create a process map of the existing system (Process Maps discussed in Chapter 4: Six sigma methodology - Define)
- Define the problem to be solved. This could be a critical requirement or Y variable. (Discussed in chapter 2: Stakeholders, customers and financial measures)
- Put a team together who have good knowledge of the process and understand the problems involved with the process
- Conduct a brainstorming or Nominal Group Technique session (Discussed in chapter 3: Setting up and managing a six sigma project). In the session, determine all the causes of the problem.
- Categorize the causes identified into groups and subgroups. A popular way to do this is through using Affinity diagrams (Discussed in chapter 3: Setting up and managing a six sigma project).
- Once groups and subgroups are available, create an Ishikawa diagram using 3 steps:
6A. Draw a box on the far right side where the problem under consideration is written down.
6B. Draw a horizontal arrow which points to the box on the right
6C. Write the names of categories above and below the horizontal line. Start with high level groups and expand each group (up to 3 or 4 levels). Write down the detailed cause data for each category.
In DMAIC, for Analyze, within Tools what does FMEA stand for?
Failure Modes and Effects Analysis
In DMAIC, for Analyze, within Tools who developed FMEA and when?
Failure Mode and Effects Analysis (FMEA) was formally used in the Airlines industry in 1960’s.
In DMAIC, for Analyze, within Tools what are the benefits of FMEA?
FMEA is a tool to:
- Identify effects or consequences of a potential product or process failure
- Identify methods to eliminate or reduce the chance of a failure occurring
In DMAIC, for Analyze, within Tools what other tools are used to create a FMEA?
Information from Process Map, Ishikawa Diagram and QFD are used in creation of FMEA
In DMAIC, for Analyze, within Tools what are the steps to complete in FMEA analysis?
FMEA Analysis Steps:
- Identify Potential failure modes
- Identify Potential failure effects
- Determine the severity rating for the effect
- Identify potential causes
- Determine the occurrence rating
- Perform Null hypothesis (optional)
- Determine P-value (optional)
- Describe Current Controls
- Determine the Detection Rating
- Calculate Risk Priority Number (RPN)
- Determine corrective action to be taken
In DMAIC, for Analyze, within Tools what is Identify Potential failure modes in FMEA analysis?
Identify Potential failure modes: Failure modes are physical description of a failure. (e.g. let us consider a case study where the manufacturing department in our company has manufactured an ear thermometer which is used to register body temperature via the ear canal. So, one potential failure mode is “Thermometer not working properly.”)
In DMAIC, for Analyze, within Tools what steps are optional in FMEA analysis?
- Perform Null hypothesis (optional)
- Determine P-value (optional)
In DMAIC, for Analyze, within Tools what is Identify Potential failure effects in FMEA analysis?
Identify Potential failure effects: Failure effects are the impact of failure on the customer i.e. the “Y” variable (e.g. However, the thermometer registers wrong temperature than the actual temperature of the patient. So, the potential failure effect here is “Wrong Temperature registered.”) Please note that there could be more than one potential failure effect or Y variable.
In DMAIC, for Analyze, within Tools what is Determine the severity rating for the effect in FMEA analysis?
Determine the severity rating for the effect: Severity is a rating corresponding to the seriousness of an effect. This is done in a scale from 1 to 10: 1: failure has least impact, 10: failure has maximum impact. (e.g. the team decides that measuring of wrong temperature is a very critical issue and hence assigns a severity rating of 9)
In DMAIC, for Analyze, within Tools what is Identify potential causes in FMEA analysis?
Identify potential causes: These are the low level bones of the Ishikawa diagram. They correspond to the Vital X’s or root causes for the problem identified. (e.g. it was determined that a failure cause for the problem is that thermometer was not calibrated properly). Please note that for each effect, there could be more than one potential failure cause. Similarly there could be multiple effects for each failure cause.
In DMAIC, for Analyze, within Tools what is Perform Null hypothesis in FMEA analysis?
Perform Null hypothesis (optional): This will be covered in detail in a black belt course. A null hypothesis is used to determine if there was any difference between the failure modes (e.g. in this case, the null hypothesis would be “There is no difference between calibration scales of thermometers”)
In DMAIC, for Analyze, within Tools what is Determine the occurrence rating in FMEA analysis?
Determine the occurrence rating: Occurrence is a rating scale of the possibility that a failure effect and its corresponding failure cause will occur in the current system. This is done in a scale from 1 to 10: 1: failure very unlikely, 10: failure certain. (e.g. the team decides that measurement of wrong temperature due to wrong calibration of thermometer has a low occurrence and assign it a value of 4)
In DMAIC, for Analyze, within Tools what is Determine P-value in FMEA analysis?
Determine P-value (optional): This will be covered in detail in a black belt course. This represents the probability of making an incorrect decision by rejecting a true null value. (e.g. in this example, the p-value was determined to be 0.04)
In DMAIC, for Analyze, within Tools what is Determine the Detection Rating in FMEA analysis?
Determine the Detection Rating: The detection rating corresponds to the probability that current controls would be able to detect potential failure modes before the product is released to the customer. This is done in a scale from 1 to 10: 1: will detect failure, 10: almost certain that will not detect failure. (e.g. in this case, the team decides that there is a very low probability that current controls will detect error - hence they provide a low detection rating of 8)
In DMAIC, for Analyze, within Tools what is Describe Current Controls in FMEA analysis?
Describe Current Controls: The team determines and describes the controls which are in place to ensure that the failure mode does not occur before the product goes out to the customer (e.g. in this case, random trials on thermometers on small samples is done to find out if some thermometers do not register temperature accurately)
