Scatter Diagram

Graph that plots pairs of numerical data on X and Y axes to reveal potential relationships between two variables. One of the 7 QC Tools. Shows whether correlation exists (positive, negative, or none) but cannot prove causation. Used in DMAIC Analyze phase, 8D D4 root cause verification, and A3 root cause analysis. Stronger correlation appears as tighter clustering along a line. Example: plotting temperature vs. defect rate to see if relationship exists. Must be followed by statistical analysis or experimentation to confirm causation.