Basic tool of statistical process control. It consists of a run chart, together with statistically determined upper and lower control limits and a centerline.

Question

Options

• AControl Chart
• BConfidence Interval
• CStatistical Control Process
• DControl Plan

• A
  93% (27)
• C
  3% (1)
• D
  3% (1)

Explanation

Control Chart (A) is correct because it is precisely defined as a run chart augmented with a centerline (typically the process mean) and statistically derived upper and lower control limits (UCL/LCL), used to monitor whether a process is in statistical control over time.

Confidence Interval (B) is a statistical range estimating where a population parameter lies - it's a standalone inferential statistic, not a process monitoring tool with control limits plotted over time. Statistical Control Process (C) reverses the actual term ("Statistical Process Control"), which is the broader methodology - the Control Chart is one tool within that methodology, not the methodology itself. Control Plan (D) is a quality document listing how to monitor and control process inputs/outputs, but it's a planning document, not a chart with plotted data and control limits.

Memory tip: Think "Control Chart = run chart with a fence" - the UCL and LCL are the fences that signal when a process has gone out of control, and the centerline is the path down the middle.

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