To construct a time series graph, we must look at both pieces of our paired data set. We start with a standard Cartesian coordinate system. The horizontal axis is used to plot the date or time increments, and the vertical axis is used to plot the values of the variable that we are measuring. By doing this, we make each point on the graph correspond to a date and a measured quantity. The points on the graph are typically connected by straight lines in the order in which they occur.

Example

The following data shows the Annual Consumer Price Index, each month, for ten years. Construct a time series graph for the Annual Consumer Price Index data only.

Year	Jan	Feb	Mar	Apr	May	Jun	Jul
2003	$181.7$	$183.1$	$184.2$	$183.8$	$183.5$	$183.7$	$183.9$
2004	$185.2$	$186.2$	$187.4$	$188.0$	$189.1$	$189.7$	$189.4$
2005	$190.7$	$191.8$	$193.3$	$194.6$	$194.4$	$194.5$	$195.4$
2006	$198.3$	$198.7$	$199.8$	$201.5$	$202.5$	$202.9$	$203.5$
2007	$202.416$	$203.499$	$205.352$	$206.686$	$207.949$	$208.352$	$208.299$
2008	$211.080$	$211.693$	$213.528$	$214.823$	$216.632$	$218.815$	$219.964$
2009	$211.143$	$212.193$	$212.709$	$213.240$	$213.856$	$215.693$	$215.351$
2010	$216.687$	$216.741$	$217.631$	$218.009$	$218.178$	$217.965$	$218.011$
2011	$220.223$	$221.309$	$223.467$	$224.906$	$225.964$	$225.722$	$225.922$
2012	$226.665$	$227.663$	$229.392$	$230.085$	$229.815$	$229.478$	$229.104$

Year	Aug	Sep	Oct	Nov	Dec	Annual
2003	$184.6$	$185.2$	$185.0$	$184.5$	$184.3$	$184.0$
2004	$189.5$	$189.9$	$190.9$	$191.0$	$190.3$	$188.9$
2005	$196.4$	$198.8$	$199.2$	$197.6$	$196.8$	$195.3$
2006	$203.9$	$202.9$	$201.8$	$201.5$	$201.8$	$201.6$
2007	$207.917$	$208.490$	$208.936$	$210.177$	$210.036$	$207.342$
2008	$219.086$	$218.783$	$216.573$	$212.425$	$210.228$	$215.303$
2009	$215.834$	$215.969$	$216.177$	$216.330$	$215.949$	$214.537$
2010	$218.312$	$218.439$	$218.711$	$218.803$	$219.179$	$218.056$
2011	$226.545$	$226.889$	$226.421$	$226.230$	$225.672$	$224.939$
2012	$230.379$	$231.407$	$231.317$	$230.221$	$229.601$	$229.594$

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Uses of a Time Series Graph

Time series graphs are important tools in various applications of statistics. When recording values of the same variable over an extended period of time, sometimes it is difficult to discern any trend or pattern. However, once the same data points are displayed graphically, some features jump out. Time series graphs make trends easy to spot.