Picture One Series—131
Picture One Series
Our soup-to-nuts example graphed three interest rates together. Now we step back and for the sake of simplicity look at the various graphic views available for a single series, all of which are available by opening a series window and choosing View/Graph…. All these graph types are available for Groups as well, as are additional types discussed in Group Graphics below.
Line Graph (…and Dot Plots)
A series line graph is just like the group line graph we saw above, except it only shows a single series. The line graph plots the value of the series on the vertical axis against the date on the horizontal axis.
132—Chapter 5. Picture This!
An EViews Dot Plot is a line graph with the lines replaced with little circles. Series in a dot plot are indented a little to improve their visual appearance.
Area Graph
An area graph is a line graph with the area underneath the line filled in. The same information is displayed in line and area graphs, but area graphs give a sense that higher values are “bigger.” Interest rates are probably better depicted as line graphs. In contrast, an area graph of the federal debt held by the public emphasizes that the U.S. national debt is one whole heck of a lot more than it used to be.
Picture One Series—133
Bar Graph
A bar graph represents the height of each point with a vertical bar. This is a great format for displaying a small number of observations; and a crummy format for displaying large numbers of observations. The figure to the right shows federal debt for the first observation in each decade. Note that EViews has drawn vertical lines to indicate breaks in the sample.
Bar labels can be added with the click of a radio button in the Fill Areas tab of the Graph Options dialog. An example is shown to the right. Note that we have also used the options page to add a neat fade effect to the bars.
134—Chapter 5. Picture This!
Spike Graph
A spike graph is just like a bar graph—only with really skinny bars. It’s especially useful when you have too many categories to display neatly with a bar graph. Here’s a version of our debt graph, using spikes to show the first quarter of each year with padding for excluded obs.
Seasonal Graphs
The standard line graph to the right shows U.S. retail and food service sales over a dozen years. Notice the regular spikes. How fast can you say “Christmas?”
Picture One Series—135
Change the Graph type to Seasonal and the right-hand side of the Graph Option dialog changes to give you choices of two kinds of seasonal graphs.
Paneled lines &
means draws one line graph for each season, and also puts in a horizontal line to mark the seasonal mean. Since our retail sales data (“Retail Sales.wf1”) is in a monthly workfile, that means twelve lines.
Using a Paneled lines & means graph it’s easy to see that December sales are relatively high and that sales in January and February are typically low.
136—Chapter 5. Picture This!
Multiple overlayed lines graphs also provide one line for each season, but use a common date axis. For our retail sales data, the Multiple overlayed lines graph does a particularly good job of showing how December (higher) and January and February (lower) compare to the remaining months.
Distribution, Quantile-Quantile, and Boxplots
Distribution graphs, quantile-quantile plots, and boxplots provide pictures of the statistical distribution of the data, rather than plotting the observations directly. (A histogram is probably the most familiar example.) These graphs are discussed in Chapter 7, “Look At Your Data”, on page 195.
Axis Borders
Even though discussion of distribution graphs awaits Chapter 7, we’ll sneak in one marginal comment. EViews lets you decorate the axes of most graphs with small histograms or other distribution graphs by using the Axis borders: menu. This is a great technique for looking at raw data and distribution information together.