Certified Quality Engineer (CQE) Practice Exam 2025 - Comprehensive All-in-One Study Guide for Exam Success!

When a process is described as being in statistical control, centered on target, and having a ± 4σ spread that equals the specification range, it offers a clear picture of how the process performance relates to the specifications set by the organization.

A process capability index (Cpk) measures how well a process is performing relative to its specification limits while considering the process mean's position relative to the target. In this scenario, since the process is centered and operates within a ± 4σ spread, it indicates that the variability is well-controlled and fits decisively within the defined specifications.

When the ± 4σ spread fits exactly within the specification range, it suggests that the process capability is high. Specifically, a Cpk of 1.33 is typically viewed as an indication that the process is capable, meaning the output consistently meets the specifications, with some buffer against variability. Cpk values over 1.0 generally signify that the process is capable of producing items that meet requirements, while a value of 1.33 signifies that the process is not only capable but also has a decent margin for variations, affirming that the process outputs are likely to remain within specification limits almost all the time.

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