Graphs of Time Series

A time  series  is a sequence of values  corresponding  to successive points  of time. Time  series  are  graphed  with time  on the x axis  and the  other variable  under  consideration  on  the y axis. Such  a graph is called  historigram graphs of time  series  can  be made  in two  types of scales.

a. Natural  scale or

b.Ration scale

With  natural  scale  there are two  types  or graphs:

Absolute historigram  here we use  original  values

Index  historigram  here we use  index  number or relative values.

Sometimes false base line  in the vertical scale  is used  where  the portion  of the  scale  which lies between  zero  and the smallest  values  of the  variable  is omitted .

To draw  an absolute historigram take time (year months etc.)along x axis and  original  values  along y axis. Plot  the point  and join  them by  straight lines.

If more than one time  series pertaining to the related phenomena and belongs to the same period  are  to be  shown  on a graph then the scale  on y axis is kept the same. The curves of for  each time series are shown  by different  types of lines. However  if two  time series are expressed in  two  different  units  then we  will have  two  scales one on the left  and the other on the right.