This is one dimension diagram, is used when the number of items is very large. There are four type of line diagram.

(a) Simple Line Diagram : In this time variable is ploted on x-axis and other variable is taken on y-axis.

(b) Logarithmic or ratio chart : When the time series data exhibit a wide range of fluctuations, them time plot on x-axis and logarithmic values of other variable is ploted on y-axis.

(c) Multiple line Chart : This is useful when two or more related time series data expressed in the same unit.

(d) Multiple axis chart : This is useful when two or more related time series data expressed in the different units.