Correlation

Positive correlation goes up. Negative goes down. No correlation has no pattern.

Line of Best Fit

A straight line drawn through the middle of the plots, with roughly equal numbers of points on both sides.

Outliers

Points that don't fit the general trend. They should be ignored when drawing the line of best fit.

Reading from the Line

Use your line of best fit to estimate one value given another (Interpolation).

Interpolation vs Extrapolation

Interpolation (estimating inside your data range) is reliable. Extrapolation (going beyond the range) is risky and often unreliable.

Causation vs Correlation

Just because two things are correlated doesn't mean one CAUSES the other.

Example: Ice cream sales and shark attacks are correlated, but both are caused by hot weather!

Equation of Best Fit

Sometimes you might be asked to find the equation (y = mx + c) of your trend line.