notes/education/statistics/Correlation and Regression.md

(Chapter 8, STAT 1040)

Correlation

Scatter Diagrams

A scatter diagram or scatter plot shows the relationship between two variables. One variable is on the X axis, the other on the Y axis.

Association

• Positive association is demonstrated when the dots are trend upward as x increases.
• Negative association is demonstrated when the the dots trend downward as x increases.
• Strong association is demonstrated when dots are clustered tightly together along a line.
• Weak association is demonstrated when dots are not clustered tightly.

Correlation

Correlation is between -1 and 1. Correlation near 1 means tight clustering, and correlation near 0 means loose clustering.

Terminology

| Term | Definition | | r | Correlation Coefficient |