<p style="text-align:justify"><span style="font-size:14px"><span style="color:black">Suppose that we want to study the temperature range of a region for an entire month. Every day at noon we note the temperature and write this down in a log. A variety of statistical studies could be done with these data. We could find the mean or the median temperature for the month. We could construct a histogram displaying the number of days that temperatures reach a certain range of values. However, all of these methods ignore a portion of the data that we have collected.</span></span></p>

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<p style="text-align:justify"><span style="font-size:14px"><span style="color:black">One feature of the data that we may want to consider is that of time. Since each date is paired with the temperature reading for the day, we don&lsquo;t have to think of the data as being random. We can instead use the times given to impose a chronological order on the data. A graph that recognizes this ordering and displays the changing temperature as the month progresses is called a time series graph.</span></span></p>

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<p><span style="font-size:14px">Constructing a Time Series Graph</span></p>

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<p style="text-align:justify"><span style="font-size:14px"><span style="color:black">To construct a time series graph, we must look at both pieces of our&nbsp;<strong>paired data set</strong>. 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.</span></span></p>