Free Certified Six Sigma Green Belt Questions and Answers — Questions and Answers

Question 1: The process of gathering customer needs and turning them into requirements is known as:

QFC
Requirements Manipulation
Voice of the Process
Voice of the Customer (Correct answer)

Correct answer: Voice of the Customer

The process of gathering customer needs and translating them into measurable requirements is known as the Voice of the Customer (VOC). VOC is a critical Lean Six Sigma concept that involves systematically collecting and understanding customer expectations, preferences, and pain points. These insights are then used to define Critical-to-Quality (CTQ) characteristics, ensuring that process improvement efforts are aligned with what truly matters to the customer.

Question 2: Which of the items below best illustrates how a SIPOC diagram develops?

Project Charter
Critical-to-Quality Requirements (Correct answer)
Voice of the Customer
A Process Map

Correct answer: Critical-to-Quality Requirements

A SIPOC (Suppliers, Inputs, Process, Outputs, Customers) diagram is a high-level process map used in the Define phase of DMAIC. While the Voice of the Customer (VOC) provides the initial understanding of what the customer wants, the SIPOC diagram helps to define the project scope by identifying the key elements of a process. It specifically helps in linking the Critical-to-Quality (CTQ) requirements, derived from VOC, to the process outputs and inputs, ensuring the process is designed to meet those critical needs.

Question 3: Two control charts are used by the X Bar R Chart to track a process. Describe them.

Mean and Variance
Grand Average and Variance
Mean and Standard Deviation
Mean and Range (Correct answer)

Correct answer: Mean and Range

The X-bar and R chart is a type of statistical process control (SPC) chart used for variable data when samples are collected in subgroups. It consists of two separate charts that work in conjunction. The X-bar chart monitors the process mean (average of subgroups) to detect shifts in the central tendency, while the R chart monitors the process range (difference between the maximum and minimum values within each subgroup) to detect changes in process variability.

Question 4: A business receives 12,000 orders each month. There could be 4 faults with each order. How many chances for faults are offered on average per year?

84,000
144,000
576,000 (Correct answer)
1,000,000

Correct answer: 576,000

To calculate the average number of chances for faults per year, first determine the total opportunities per month. With 12,000 orders each month and 4 fault opportunities per order, there are 12,000 * 4 = 48,000 opportunities per month. To find the annual total, multiply this by 12 months: 48,000 * 12 = 576,000 opportunities per year. This metric is crucial for understanding the potential for defects in a process.

Question 5: How would you describe control limits and specification limits?

Control Limits are set by the customers; Specification Limits are derived by the process
Control Limits are typically 3 standard deviations from the mean; Specification Limits are typically 3 standard deviations from the target
There is no difference between the terms; both are used to indicate if a process is in control
Control Limits are derived by the process; Specification Limits are set by the customer (Correct answer)

Correct answer: Control Limits are derived by the process; Specification Limits are set by the customer

Control Limits and Specification Limits serve different purposes and are derived from different sources. Control Limits are statistically derived from the actual performance data of a process, typically set at +/- 3 standard deviations from the process mean, indicating the natural, expected range of variation when the process is stable. In contrast, Specification Limits are determined by the customer or design requirements, defining the acceptable range of performance for a product or service to meet customer needs.

Question 6: What three characteristics of Six Sigma best capture why Senior Management finds it to be an effective approach for decreasing variance and enhancing processes?

Customer Focused, Data Driven, ROI Oriented (Correct answer)
Data Driven, Methodical, ROI Oriented
Data Driven, Creative, Streamlined
Customer Focused, Statistical Emphasis, Conformity - Driven

Correct answer: Customer Focused, Data Driven, ROI Oriented

Senior Management finds Six Sigma effective due to its core characteristics: it is Customer Focused, meaning all improvements are driven by what matters to the customer; it is Data Driven, relying on statistical analysis and facts to make decisions and measure progress; and it is ROI Oriented, ensuring that improvement projects deliver tangible financial benefits and a clear return on investment. These three aspects align Six Sigma with strategic business objectives.

Question 7: Which kind of human error is usually restricted to a specific task?

selective
willful
inadvertent
technique (Correct answer)

Correct answer: technique

Among the given options, 'technique' best describes a human error usually restricted to a specific task. A technique error occurs when an individual fails to correctly execute a particular procedure or method, often due to lack of skill, improper training, or deviation from standard operating procedures. This type of error is localized to the specific task being performed, unlike broader categories of error.

Question 8: What Six Sigma is best described as is:

A management methodology that is primarily focused on achieving financial results.
A customer-focused problem-solving methodology used exclusively within the manufacturing sector. (Correct answer)
A management methodology that uses only statistical tools to improve customer experience.
A customer-focused problem-solving methodology that uses powerful statistical tools to reduce variation and improve processes.

Correct answer: A customer-focused problem-solving methodology used exclusively within the manufacturing sector.

Six Sigma is best described as a customer-focused problem-solving methodology that uses powerful statistical tools to reduce variation and improve processes. It is not exclusive to manufacturing, nor is it solely focused on financial results or only statistical tools. Its comprehensive approach aims to achieve near-perfect quality by systematically identifying and eliminating the root causes of defects and inefficiencies, ultimately enhancing customer experience.

Question 9: The best definition of a normal distribution is:

Bell-shaped, symmetrical about the mean, a single mode. (Correct answer)
Symmetrical about the mean, bell-shaped, discrete data.
Bell-shaped, a variance of 1, the mean=median=mode.
Un-Symmetrical about the mean, a natural tolerance of three standard deviations, unimodal.

Correct answer: Bell-shaped, symmetrical about the mean, a single mode.

A normal distribution is best defined by its characteristic shape and properties. It is bell-shaped, meaning its graph resembles a bell curve, and it is perfectly symmetrical about its mean. Furthermore, a normal distribution has a single mode, where the mean, median, and mode are all equal, representing the peak of the distribution. These features make it a fundamental concept in statistics for modeling many natural phenomena.

Question 10: Platykurtic is a shape that is:

Same as a Normal Distribution.
Flatter than the Normal Distribution. (Correct answer)
Narrower than a Normal Distribution.
None of the above

Correct answer: Flatter than the Normal Distribution.

Platykurtic is a term used to describe the kurtosis of a probability distribution, which relates to the 'tailedness' or 'peakedness' of its shape. A platykurtic distribution is flatter than a normal distribution, meaning it has a lower, broader peak and lighter tails. This indicates that the data points are more spread out from the mean, with fewer extreme outliers compared to a normal distribution.

Question 11: A process is stable and under control. What kinds of variations are present in the process?

Natural Variation (Correct answer)
Non-random variation
Special Cause variation
Out-the-ordinary variation

Correct answer: Natural Variation

When a process is stable and under control, it means that only common cause variation, also known as natural variation or inherent variation, is present. This type of variation is intrinsic to the process itself, is random, and is predictable within statistical limits. The absence of special cause variation indicates that the process is operating consistently, even if the level of natural variation is still too high relative to customer specifications.

Question 12: Specify the control char(s) that are most sensitive to time as data:

P Chart
Np chart
Individuals and Moving Range
X bar R Chart (Correct answer)

Correct answer: X bar R Chart

The X-bar and R chart is most sensitive to time as data because it monitors both the average (X-bar) and the range (R) of subgroups taken sequentially over time. This allows for the detection of shifts in the process mean or changes in process variability as they occur chronologically. By tracking these metrics over time, the chart can identify trends, cycles, or other patterns that indicate a process change.

Question 13: In the control chart, you can see that a process is trending as you monitor it. What is likely to be the problem?

Wear of machinery
Changes in materials (Correct answer)
New operators
Different shifts

Correct answer: Changes in materials

A trend in a control chart, characterized by a consistent upward or downward movement of data points, often indicates a gradual, systemic change affecting the process. Changes in materials, such as a new batch with slightly different properties or gradual degradation of a raw material, can lead to such a sustained shift in process output over time. This is a common root cause for trending behavior observed in control charts.

Question 14: A equipment installation has a variance of 36 square minutes. The Standard Deviation is what?

6 minutes (Correct answer)
Need to know the mean to compute
18 minutes
72 minutes

Correct answer: 6 minutes

Variance is the square of the standard deviation. Therefore, to find the standard deviation, you must take the square root of the variance. In this case, the variance is 36 square minutes, so the standard deviation is the square root of 36, which equals 6 minutes. The unit of standard deviation is the same as the original measurement unit.

Question 15: There is intrinsic volatility in a process that you are tracking over time. What method should you employ to control the process?

Continually and gradually improve the stable process (Correct answer)
Stop the process, identify the causes, and eliminate them
Take immediate action to identify root causes of the common cause variation
Increase the specification limits to ensure the process is capable

Correct answer: Continually and gradually improve the stable process

If a process is stable and under control (meaning only common cause variation is present), but its intrinsic volatility is still too high relative to customer specifications, the appropriate action is to continually and gradually improve the stable process. This involves making fundamental changes to the process system itself to reduce the inherent common cause variation, rather than reacting to individual data points or increasing specification limits.

Question 16: If there is no connection between two variables, then

As one variable increases, the other variable decreases
As one variable decreases, the other variable increases
As one variable changes, one cannot predict a value for the other variable (Correct answer)
As one variable decreases, the other variable decreases

Correct answer: As one variable changes, one cannot predict a value for the other variable

If there is no connection or correlation between two variables, then changes in one variable provide no information about the likely behavior or value of the other variable. Their movements are independent of each other. Consequently, as one variable changes, one cannot predict a value for the other variable, as there is no discernible relationship between them.

Free Certified Six Sigma Green Belt Questions and Answers

The process of gathering customer needs and turning them into requirements is known as: