Examining Relationships Chapter 3

Scatterplots A scatterplot shows the relationship between two quantitative variables measured on the same individuals. The explanatory variable is graphed on the x-axis and the response variable is graphed on the y-axis. Scatterplots reveal the strength, type, and direction.

Patterns (STD’s) Strength: determined by how close the points in the scatterplot are linear (“Strong, moderate, or weak”) Type: linear is preferred, but curves and clusters are significant (“linear or nonlinear”) Direction: variables are either positively associated or negatively associated (“positive or negative”)