Free LSSGB sample questions

Correct answer: Control Chart

A Control Chart is the primary tool used in the Control phase for monitoring a process over time. It helps distinguish between common cause variation (inherent in the process) and special cause variation (due to specific, identifiable causes). By plotting cycle time data on a control chart, the team can visually track performance, verify the stability of the improved process, and quickly react to any signals that indicate the process has gone out of control.

Correct answers: Design Failure Mode and Effects Analysis (DFMEA); Fault Tree Analysis (FTA)

Correct answer: True

This statement accurately defines an interaction effect in DOE. It's a crucial concept because it means factors cannot be optimized independently. For example, the optimal temperature for a chemical reaction might be different depending on which catalyst is used. Ignoring interactions can lead to incorrect conclusions and suboptimal process settings.

Correct answer: It is not measurable or specific.

An effective problem statement should be SMART (Specific, Measurable, Achievable, Relevant, Time-bound). This statement is vague. It doesn't quantify the problem (e.g., 'delivery times average 10 days against a target of 3'), specify the scope (e.g., 'for North American customers'), or indicate the time frame over which the problem has been observed. Without these measurable and specific details, the team cannot establish a baseline or measure success.

Correct answer: The process is not capable of meeting the target, and its average is off-center.

A Cpk value less than 1.0 indicates that the process is not capable of consistently meeting its specification limits. A common industry benchmark for a capable process is a Cpk of 1.33 or higher. The 'k' in Cpk specifically accounts for how centered the process average is relative to the specification limits. A low Cpk value implies either the process variation is too wide, the process average is not centered between the specification limits, or both. Therefore, a Cpk of 0.45 definitively means the process is not capable and likely off-center.

Correct answer: 2-sample t-test (Welch's t-test)

The 2-sample t-test is used to compare the means of two independent groups. Since the data is normally distributed, a parametric test like the t-test is appropriate. Because the variances are unequal, the specific version of the 2-sample t-test that does not assume equal variances (often called Welch's t-test) must be used. A Paired t-test is for dependent samples, ANOVA is for three or more groups, and the Mann-Whitney U test is a non-parametric alternative used when the data is not normally distributed.

Correct answer: Fractional Factorial Design

A Fractional Factorial Design is an experiment where only a subset (a fraction) of the runs from a full factorial design are performed. In this case, a full factorial experiment with three factors at two levels each would require 2^3 = 8 runs. By conducting only 4 runs, the team is using a half-fraction design. This is done to save time and resources, at the cost of confounding some effects (usually higher-order interactions are confounded with main effects).

Correct answers: The specific process characteristic being controlled; The measurement method and sample size/frequency; The reaction plan for an out-of-control condition

Correct answer: An Attribute Agreement Analysis

The inspection process generates attribute data ('Correct' or 'Incorrect'), which is discrete and categorical, not continuous. An Attribute Agreement Analysis is the specific type of Measurement System Analysis (MSA) designed for this type of data. It assesses the consistency and correctness of appraisers, evaluating how well each appraiser agrees with themselves (repeatability) and with other appraisers or a known standard (reproducibility). A variable Gage R&R is used for continuous data, and a Cpk study measures process capability, which can only be done after the measurement system is proven reliable.

Correct answer: To distinguish between necessary and unnecessary items and remove the latter.

The 'Sort' (Seiri) step is the first and foundational phase of 5S. Its primary purpose is to go through all items in a workspace—tools, materials, documents—and separate what is essential for the work from what is not. Unnecessary items are then removed, recycled, or relocated. This declutters the workspace, frees up space, and eliminates the waste of searching for needed items among clutter.