HerfstkleurenHelpdesk IBM SPSS Statistics 20

For students from Arnhem Business School
Home Codebook Data Data editing Analysis Graphs Settings Links Methods

Graphs Boxplot

In this example we use data about the tallest buildings in the world. This data comes from Wikipedia and was downloaded and edited in September 2011. Surely there is an update of this data available at the moment.
The following variables are in our data file. Height is recorded in meters. Year is the year the building was completed.


We want to show the height distribution of these sky scrapers by means of a boxplot. In this example we use Graphs > Legacy Dialogs > Boxplot...:

We have chosen for a simple boxplot and for summaries of separate variables. We filled in the dialog box as shown below:

define simple boxplot


The first Result

Clearly this graph needs editing. A title is missing. The Burj Khalifa is an extreme outlier that on its own uses half of the available image space. Do we want this or not?
Depending on the context where it will be published it might need a source.
And of course we might want to experiment with the scale on the vertical axis, gridlines, colors and the fonts that are used.

You can also see the effect of our choice for "Label cases by Building". Outliers are identified by their value for this variable; hence the name of the building is shown in the plot.

Double clicking on the chart in the SPSS output windows opens the graph in a new Chart Editor window.



If you click on a part of the graph the corresponding Properties Window appears. It might have several tabs. As an example you see the Properties Window that pops up when you click on the box of our boxplot. On the active tab you can change the colors of the fill and border of the box, but as you can see there are more tabs where you can make adjustments.

It isn't useful to show you all of these dialog boxes. There are too many of them and they all work in a similar way. You choose the options that you want and click on "Apply". The changes will show in the chart.
If you like it then keep it. Otherwise go back to the dialog and change it again.

If the Properties Window doesn't show you can activate it via the button
 properties button

Explore the other buttons of the tool bars as well:

tool buttons
properties colors 


The edited results:

boxplot edit 1 boxplot edit 2

In the plot on the left we have edited a number of things but we kept the scale intact, so that all buildings would show up in the picture and the extreme size of the Burj Kalifa is emphasized.

In the plot on the right we have changed the scale to the range [200;450]. In this way we can zoom in on the bulk of the buildings in our dataset.
We have also added some explanation of what the boxplot tells us. Whether this is useful or not depends on your readers and how familiar they are with this lesser known display. In our introductory statistics classes it helps the students understand the plot.

Note: Copying and pasting graphs into Word works fine most of the time, but not always.
As an alternative you can use the Export option in the SPSS output window.
Select in the output window the chart you want to export and from the menu choose File > Export... .
Next fill in the dialog box to get what you want.

Note: If you find it hard to add the text fields in the SPSS chart, don't hesitate to export the chart and continue your editing in another program of your choice.


Last modified 30-10-2012

Jos Seegers, 2009; English version by Gé Groenewegen.