Multiple Line Graphs — Definition

Definition

A multiple-line graph plots two or more series against a shared horizontal variable, commonly time. Each line connects observations from one series, allowing comparisons of levels, changes and movement over intervals.

The legend, axis units and spacing determine what those comparisons mean. A steeper-looking segment does not necessarily represent a greater rate if time intervals or scales differ. Connected points also do not establish the exact path between observations unless an interpolation rule is supplied.

A careful solution distinguishes observed values, calculated changes and assumptions about unobserved values.