Iassc Certified Lean Six Sigma Green Belt Free Sample Questions

The 2-sample t-test assumes that the data is normally distributed. Since the data is highly skewed, this assumption is violated, making the t-test results unreliable. The Mann-Whitney test is a non-parametric alternative that does not require normality and tests for a difference in medians, which is a more robust measure of central tendency for skewed data. Therefore, the conclusion should be based on the Mann-Whitney test, which indicates a significant difference (p < 0.05).

An I-MR (Individuals and Moving Range) chart is designed for continuous (variable) data where measurements are taken one at a time, making the logical subgroup size one. In this scenario, viscosity is a continuous measurement, and only one reading is taken per batch. Therefore, the I-MR chart is the most appropriate choice to monitor the process mean and variation between batches.

The Risk Priority Number (RPN) is calculated by multiplying the scores for Severity, Occurrence, and Detection (S x O x D). In this case, RPN = 8 x 3 x 7 = 168. The RPN is not an absolute measure but a relative one, used to rank and prioritize potential failure modes. Teams use the RPN to focus their limited resources on mitigating the highest-risk items first.

A Cpk of 0.75 indicates the process is not capable of meeting specifications. Since the process is stable, the issue is common cause variation, not special cause events. The next logical step in DMAIC is to move to the Analyze phase to find the root causes of this inherent variation.

Fishbone diagrams and the 5 Whys are primary tools used in the Analyze phase for root cause analysis. They help the team systematically explore and identify the underlying factors (the 'vital few' x's) that are contributing to the process variation and causing the low capability.

This statement is true. The core principle of a 'pull' system, a fundamental concept in Lean, is to link production directly to customer or downstream process demand. This prevents the waste of overproduction, which is often considered the worst form of waste because it generates other wastes like excess inventory, transportation, and waiting.

R-squared, also known as the coefficient of determination, measures the proportion of the variance in the dependent variable (Y) that is predictable from the independent variable(s) (X). An R-sq of 85% means that 85% of the observed variation in the number of defects is explained by the linear relationship with the number of lines of code. It does not imply causation.

The principle of 'garbage in, garbage out' is critical in Six Sigma. Before any process analysis can be trusted, the measurement system itself must be validated. The lack of synchronized systems and manual entry points to significant potential measurement error. The most critical step is to establish clear operational definitions for exactly what 'Order-to-Delivery Time' and its components mean, and then perform an MSA (like a Gage R&R study, modified for a transactional process) to understand and quantify the error in the data. Without this, any conclusions drawn in the Analyze phase would be invalid.

A Pareto Chart is a bar chart where the bars are ordered from highest frequency to lowest, illustrating the 80/20 rule (Pareto Principle). This principle states that for many events, roughly 80% of the effects come from 20% of the causes. The chart visually separates the 'vital few' causes that contribute most to the problem from the 'trivial many', allowing teams to focus their efforts effectively.

Internal Failure Costs are incurred when defects are discovered before the product or service is delivered to the customer. Examples include the cost of rework, scrapping defective products, downgrading products, and machine downtime caused by defects. These are costs of nonconformance found within the organization.

This is a Control Method, specifically a prevention-type Poka-Yoke. It physically prevents the error from occurring. Warning methods would only signal that an error has been made (e.g., a light or buzzer), but would not stop it from happening. The asymmetric pin design makes it impossible to assemble the part incorrectly, thus preventing the defect at the source.