Scatter plot
A scatter plot graphs paired observations of two variables as points on a coordinate plane, revealing the strength, direction and form of their relationship. It is the essential first step before correlation analysis or regression.
See it move
Each point on the plot represents one paired observation, one variable on each axis. Reading the cloud reveals direction, whether higher x accompanies higher or lower y, form, whether the pattern is straight or curved, and strength, how tightly points cluster. An OLS line is fitted only after this visual check, since a correlation coefficient alone can mask a curved relationship.
Check yourself
An analyst plots advertising spend against weekly revenue for 60 stores and observes that the data points cluster tightly around a line running from the lower-left to the upper-right. She concludes that advertising spending causes higher revenue. What is the key flaw in this conclusion?