Is the process stable? If not, in what months is it not stable? Answer: Yes

The correct answer is A. Yes. Option A is correct because the process demonstrates statistical stability - all data points fall within the established control limits with no special cause variation (such as points outside control limits, runs, trends, or other non-random patterns). When a process is stable…

Control Phase

Question

Is the process stable? If not, in what months is it not stable? Answer: Yes

Options

AYes
BNo

How the community answered

(44 responses)

A
84% (37)
B
16% (7)

Explanation

Option A is correct because the process demonstrates statistical stability - all data points fall within the established control limits with no special cause variation (such as points outside control limits, runs, trends, or other non-random patterns). When a process is stable, it is said to be "in control," meaning variation is due only to common causes inherent to the system.

Option B is incorrect because selecting "No" would require identifying specific months where the process exhibited out-of-control signals, such as points beyond the 3-sigma control limits or suspicious patterns like eight consecutive points on one side of the centerline - none of which are present here.

Memory tip: Think of a stable process like a flat road - if the car (data) stays between the guardrails (control limits) without swerving, the drive (process) is stable. If it jumps outside or shows a consistent drift, that's when you flag specific months.

Topics

#process stability#control charts#out-of-control points#SPC

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