The choice of a Line graph to display your data is appropriate when the data in your data table has a "continuous" nature. The most common (appropriate) use of the line graph is found in describing events that have been captured in time. For instance, temperatue is measured at regular time intervals, say on the hour. While there are no "actual" readings between 9:00 and 10:00, we know that during this time interval that the temperature probably made a smooth change from the temperature at 9:00 and the temperature at 10:00. This "continuous" nature of time lets us connect the dots in a line.
Excel doesn't ask whether the data you collect is continuous or not, it just lets YOU select the chart. To prove this fact, we will illustrate how to display your data in a line graph even when you shouldn't choose a line graph!
First let's look at a data table.
It is easy to see that this data is NOT, continuous in nature, but we move along anyway.
We select the data we need from our data table. This is accomplished by clicking and dragging across the diagonal from Cell A1 to B6 or from B1 to A6. Either way, we select a block of our data table.
Now
we tell Excel that we want to insert a chart. We may use the Menu and Insert
+ Chart or click on the Chart Wizard button on
the toolbar.
This
will introduce the first of 4 panels of the Wizard. You
identify the type or category of graph you need by selecting
from the left window.
The different kinds of graphs of that type are then displayed in the right window.
If you click once on a particular type of line graph, you will see a short phrase giving you a hint as to what that graph is all about.
Even though WE know the selection of line graph is appropriate, Excel doen't know and so we press on to the Source of the Data.
Excel
doesn't know how the data is contained in the block of cells we selected.
We give Excel this information by accepting the Columns option since our data from the data table is displayed in columns.
The third panel lets us decorate the table with the appropriate labels to help the viewer understand about our data.
When we are satisfied, we move to the last panel which lets us tell Excel where to display the graph.
For purposes of this demonstration, we will select to have Excel display the graph as a drawing object on the spreadsheet page containing the data table.
The steps to select a line graph for an appropriate data situation and an inappropriate situation are identical. As in most situations involving decisions with a computer, the machine will do what we tell it to...even when it is the wrong decision!