Provides relationship between two variables, and provides a visual correlation coefficient.

Question

Options

• AControl Chart
• BPareto Chart
• CScatter Diagram
• DStatistical Process Control

• A
  4% (1)
• C
  91% (21)
• D
  4% (1)

Explanation

A Scatter Diagram plots two variables on X and Y axes to visually display their relationship, making the correlation (positive, negative, or none) immediately apparent - it is literally designed to show correlation between two variables.

Why the distractors are wrong:

• A. Control Chart - tracks a single process variable over time to detect variation and instability, not relationships between two variables.
• B. Pareto Chart - a bar chart that ranks causes by frequency/impact (the 80/20 rule), showing which problems matter most, not correlations.
• D. Statistical Process Control (SPC) - is a broader methodology (not a single chart) for monitoring process quality using control charts; it doesn't visualize two-variable relationships.

Memory tip: Think "Scatter = two things scattered against each other." If a question mentions two variables and correlation, the answer is always Scatter Diagram - it's the only quality tool that plots one variable against another.

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