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I'm sure you're familiar with the saying "A picture
is worth a thousand words." This concept is
especially appropriate when applied to numbers. If you've
ever tried to grasp the significance of lists and tables
of numbers, and then been able to look at them in
the form of a graph (or chart), you know exactly
what I'm talking about. A graph illustrates the
relationship between groups of numbers and helps you come
to conclusions or make decisions based on the
information the numbers supply.
For example, in Figure 1, which region shows
the most sales growth? While the Northern region in
the table at the bottom of Figure 1 has the largest
numbers, does it have the biggest increase in sales?
The graph above it says no. In addition, the spike for
the Eastern region's third quarter may have passed
unnoticed in a sea of numbers, but depicted in a
graph, the increase cries out for an explanation.
Because the visualization of numbers is so
important, spreadsheet programs like Excel include
a graphing feature. One job the software can't do
for you, however, is choose the numbers and decide
exactly what format is best to present them. So
Microsoft Excel offers you some help in that direction.
If you click the Office Assistant and ask about
"chart types," then choose to see more about "Examples
of chart types," you get a list. Each entry for a
chart type is a link to an explanation of the type of
graph, and the uses it's best for.
Once you have your data, and you have an idea how you want to present it, it's time to make
the graph. The first step is to select the data. Your
data may all be in contiguous cells, or you may wish
to make a selection that "jumps" blocks of cells. To
select noncontiguous cells, make the first
selection, then hold down the Ctrl key as you drag over the
additional blocks of cells.
Next you start the Chart Wizard by clicking the toolbar button, or by choosing Insert|Chart. In
four steps, you select the type of chart, make changes
to the data selection and how it's presented, have an
opportunity to change the textual information on
the graph (titles, axes, legend, and data labels), and
finally, choose whether the graph should be on its
own worksheet, or be created as an object on
another sheet. All these settings except the last one can
be changed relatively easily later by right-clicking on
the relevant part of the chart.
When you create a chart, the most difficult
concept is how the data series should be arranged: in rows
or in columns. As a case in point, take a look at the
two graphs for the same table shown in Figure 2.
The data series are viewed in rows for the graph on
the left and in columns for the one on the right. Put
differently, the row headings are used in the legend
in the first case. In the second, the column headings
are used in the legend and the other headings provide
the labels for the X-axis. So which do you want to
highlight: the annual comparison of shop types or the
development of each shop type over a number of years?
The second step in the Chart Wizard makes it
easy to switch between data series in rows and data
series in columns—as long as your data selection
includes only the information you want in the chart (see
Figure 3). As soon as there is extraneous
information, (for example, suppose the table title "Sales" were
in cell A2 in the same row as the column headers)
the graphing applet becomes confused. You can convince it to use only the relevant data, but it's tricky.
If the number of rows and/or columns you want
to include in the chart changes, you don't have to
recreate the graph from scratch. You can change the
data range in this same dialog box (to access it, click
once on the graph, so the charting menus are
available, then choose Chart|Source Data). Select and
delete the old data range information, then drag across
the correct range in the Excel worksheet. You can still
select in the worksheet while the dialog box is visible.
You may find your graph doesn't convey all the necessary
information. Suppose you'd like to highlight a data
point or provide an explanation for that spike in Figure 1. In Excel
it's easy: use the tools on the Drawing toolbar to
add circles, text boxes, or whatever else you need.
Graphs aren't used only in spreadsheets; they're an important
element in reports and presentations as well. With Microsoft Office, you can copy and paste a
graph from Excel into a Word document or
PowerPoint presentation. Or you can create the graph entirely
in either of these applications by choosing Insert|Object|Microsoft Graph.
Now it's up to you to discover what graphs can
do for you to help you streamline your business!
Figure 1. The data table and its Line graph compare trends over time.
Figure 2. Reversing the data series changes a chart’s emphasis.
Figure 3. You specify the data series layout in step 2 of the chart wizard.
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