Six Sigma Green Belt Certification Exam - 4

The Define phase in Six Sigma DMAIC focuses on clearly defining the problem and project scope. Its three key deliverables are: (1) Project Charter - documenting the problem, goal, scope, and team; (2) CTQs (Critical to Quality) - translating customer needs into measurable requirements; (3) COPIS diagram - mapping the process at a high level from Customer through Supplier. These form the foundation for the remaining phases.

DPU (Defects Per Unit) measures the average number of defects per product or unit. The formula is: DPU = Total Defects ÷ Total Units (or products). This differs from DPO (Defects Per Opportunity) which divides by opportunities, and DPMO which scales to million opportunities. DPU is a straightforward metric that tells you how many defects exist per product on average.

In a box plot (box-and-whisker plot), extreme values that fall beyond the whiskers are called outliers. The whiskers typically extend to 1.5 × IQR (Interquartile Range) from the quartiles. Any data point beyond these whiskers is considered an outlier and is plotted individually as a dot or asterisk. These extreme values warrant investigation as they may represent special causes or measurement errors.

FMEA stands for Failure Mode and Effects Analysis. It is a systematic method used to identify potential failure modes in a process, product, or system, assess their severity and likelihood, and prioritize actions to prevent or mitigate them. The full name exactly matches option B, making it the correct answer.

FMEA is used during solution development and implementation to identify potential failure modes and refine the solution accordingly. By analyzing how a solution might fail (failure modes) and what the effects would be, teams can proactively modify the design or process to prevent those failures. This preventive approach ensures solutions are robust before full deployment, making 'Refining the solution based on failuremodes' the primary use.

When a production job fails due to new code changes, the immediate priority is Containment - limiting the impact and preventing further occurrence while protecting production systems. Taking it as a full GB project (A) or collecting historical data (D) are appropriate but secondary to containing the immediate problem. Leaving it as is (C) ignores the production impact. Containment is the first response in problem-solving methodology.

In Design of Experiments with full factorial design, the number of trials is calculated as levels^variables. With 3 variables at 2 levels each: 2^3 = 8 trials. This tests all possible combinations. Option C (5) might suggest fractional factorial, and option D (16) would be 2^4 for four variables.

Managing customer expectations during Voice of the Customer (VOC) collection requires transparency. Explaining your intent helps the customer understand why you are asking questions and prevents them from assuming that every suggestion they make will be immediately implemented, which maintains a professional relationship.

When one variable increases while the other decreases, they have an inverse (negative) relationship. In a positive relationship, both variables move in the same direction. 'Independent' suggests no relationship exists, and 'No Relationship' means no correlation. The correct term for opposite movement is inverse.

When dealing with continuous data and a sample size of 1 (individual observations), the Individuals and Moving Range (I-MR) chart is the appropriate tool. Option 5617 (X and Moving Range) is synonymous with I-MR. 'p' and 'np' charts are used for discrete/attribute data.

Segmentation factors must be identified before data collection so you can properly stratify the data. If you wait until after collection, you may have missed capturing critical grouping variables. Proper segmentation enables meaningful subgroup analysis.

Special cause variation comes from identifiable, assignable sources that are not part of the normal process. Unlike common cause variation which is inherent and expected, special causes are unexpected disruptions that require investigation and elimination.

For skewed data distributions, parametric measures like standard deviation are heavily influenced by outliers and skewness, making the range or non-parametric spread measures more appropriate. The range captures the full span from minimum to maximum values.

Stability Factor is defined as Q1/Q3 (first quartile divided by third quartile). This ratio measures the relative position of the quartiles and indicates the degree of skewness in the distribution. Values less than 1 indicate positive skewness, while values greater than 1 indicate negative skewness.

A Team Charter includes Business Case, Problem & Goal Statement, Scope, Team Roles, Timeline, and Resources. COPIS (Customer-Output-Process-Input-Supplier) is a SIPOC variant used in process mapping, not a component of the Team Charter itself.

Technology Case focuses on shifting the process mean to target through technology solutions like automation, equipment upgrades, or process redesign. This differs from Business Case (reduce variation) and Both Case (reduce variation AND shift mean).

The House of Quality is the central matrix in Quality Function Deployment (QFD) methodology. It translates customer needs (Voice of Customer) into technical requirements and helps prioritize features. QFD is used in Design for Six Sigma (DFSS) and product development.

Linearity measures how consistently a measurement system performs across its entire operating range - from minimum to maximum values. It's the difference in bias at different measurement levels. Stability refers to consistency over time, Repeatability to same-operator consistency, and Accuracy to closeness to true value.

Chi-Square Test is used for discrete-discrete data relationships. It tests independence between categorical variables. Regression is for continuous-continuous, ANOVA for discrete-continuous (comparing means), and t-Test for continuous data with 1-2 groups.

Goal Statement explicitly defines the improvement objective with measurable targets (e.g., 'reduce defect rate from 15% to 5% by June'). Problem Statement describes current pain, Business Case justifies the project, and Project Charter contains all elements including the Goal Statement.

Measures of central tendency describe the center or typical value of a dataset. Arithmetic mean, mode, and median are all measures of central tendency. Variance is a measure of dispersion or spread, not central tendency - it quantifies how far data points deviate from the mean. Therefore, variance is the correct answer as the option that is NOT a measure of central tendency.

Quality dimensions typically include fitness for use, conformance to requirements, and consistency. Luxury is not considered a fundamental aspect or dimension of quality - it's a market positioning or pricing strategy, not a quality characteristic. Juran's definition focuses on fitness for use, while Crosby emphasizes conformance to requirements. Luxury is about premium positioning, not quality per se.

A fully developed Critical to Quality (CTQ) tree typically includes the Customer Need, the Driver, and the CTQ Requirement (which includes a Metric and a Target). While a deadline is important for project management, it is not one of the four standard technical components of a CTQ characteristic.