Define "capability of the process" in statistical terms. Answer: Capability is a measure of the relative relationship between the "Voice of the Process" and the "Voice of the Customer." This…

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Options

• ACapability is a measure of the relative relationship between the "Voice of the Process" and the "Voice of the Customer." This relationship considers the differential between the mean and nominal of the process. The capability of a stable and normally distributed process is defined as 99.73% of its output will be in the interval between LNL(mean + 3[ R /d2]) and UNL (mean - 3[ R /d2]), given measurement data and a subgroup size betw

• A
  100% (30)

Explanation

Option A is correct because it accurately captures both the conceptual and mathematical definition of process capability - it frames capability as the relationship between what the process naturally produces ("Voice of the Process") and what the customer requires ("Voice of the Customer"), while also providing the precise statistical boundary: for a stable, normally distributed process, 99.73% of output falls within ±3 standard deviations of the mean (the natural tolerance limits, LNL and UNL). The formula uses R̄/d₂ as the estimate of process standard deviation, which is the standard approach when working with subgroup data (subgroup sizes 2–10). No other distractors are presented in this question, so A stands as the sole complete and correct definition.

Memory tip: Think of capability as a "fit check" - does the process's natural spread (±3σ, covering 99.73%) fit inside what the customer will accept? The R̄/d₂ formula is your way of estimating σ from range data, where d₂ is a control chart constant that scales the average range into a standard deviation estimate.

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