Lean Six Sigma Yellow Belt The Analyze Phase Questions and Answers — Questions and Answers
Question 1: A project team is trying to understand the fundamental reason why a specific machine repeatedly malfunctions. They begin by stating the problem and then sequentially ask the same question to drill down through layers of symptoms. Which root cause analysis tool are they using?
- Fishbone Diagram
- 5 Whys (Correct answer)
- Scatter Plot
- Histogram
Correct answer: 5 Whys
The 5 Whys is an iterative interrogative technique used to explore the cause-and-effect relationships underlying a particular problem. The primary goal is to determine the root cause of a defect or problem by repeatedly asking the question "Why?".
Question 2: In the Analyze phase, what is the primary purpose of performing a hypothesis test?
- To visually represent the frequency of different defects.
- To brainstorm all possible causes of a process issue.
- To statistically validate whether a suspected cause has a significant effect on the output. (Correct answer)
- To create a high-level map of the process stakeholders.
Correct answer: To statistically validate whether a suspected cause has a significant effect on the output.
Hypothesis testing is a statistical method used to make decisions using data. In the Analyze phase, it is used to determine if there is enough evidence to conclude that a suspected root cause (an input variable 'X') has a statistically significant impact on the project's primary metric (the output 'Y').
Question 3: A team suspects that an increase in ambient factory temperature is related to a higher number of product defects. Which tool would be most effective for visually investigating the potential relationship between these two continuous variables?
- Scatter Plot (Correct answer)
- Control Chart
- Pareto Chart
- Process Map
Correct answer: Scatter Plot
A Scatter Plot graphs pairs of numerical data, with one variable on each axis, to look for a relationship between them. It is the ideal tool for visualizing how one variable may be affecting another, such as plotting temperature against the number of defects to see if a correlation exists.
Question 4: Which of the following represents the key transition that occurs when a DMAIC project moves from the Measure phase to the Analyze phase?
- From brainstorming potential solutions to implementing them.
- From collecting baseline data and validating the measurement system to identifying and verifying root causes. (Correct answer)
- From defining the project scope to mapping the high-level process.
- From implementing a control plan to closing out the project.
Correct answer: From collecting baseline data and validating the measurement system to identifying and verifying root causes.
The Measure phase focuses on collecting reliable data to establish the current process performance (the baseline). The Analyze phase takes this data and uses various tools to drill down into why the process is performing that way, with the primary goal of identifying and validating the true root causes of the problem.
Question 5: A team analyzing a process map for an invoice payment system identifies a step where invoices sit in a queue for an average of three days waiting for approval. This waiting period consumes time but does not change the invoice or add value from the customer's perspective. How is this step best classified?
- A bottleneck
- Value-Added
- A critical control point
- Non-Value-Added (Waste) (Correct answer)
Correct answer: Non-Value-Added (Waste)
Non-Value-Added activities are steps that consume resources but do not add any value from the customer's perspective. Waiting time is one of the classic eight wastes in Lean. Since the customer does not benefit from this delay, it is considered waste and a target for elimination.
Question 6: Which of the following graphical tools is most useful during the Analyze phase for understanding the shape, center, and spread of a set of continuous measurement data?
- Run Chart
- SIPOC Diagram
- Histogram (Correct answer)
- Fishbone Diagram
Correct answer: Histogram
A histogram is a graphical representation that organizes a group of data points into specified ranges or 'bins'. It provides a visual summary of the data's distribution, showing its shape (e.g., normal or skewed), central tendency, and spread (variation), which are crucial for analysis.
Lean Six Sigma Yellow Belt The Analyze Phase Questions and Answers
A project team is trying to understand the fundamental reason why a specific machine repeatedly malfunctions.
They begin by stating the problem and then sequentially ask the same question to drill down through layers of symptoms.
Which root cause analysis tool are they using?