15. Creating Graphs

A picture is worth a thousand words

As part of the result section, key graphs need to be presented. Unfortunately, most people do no present graphs in a professional manner, so that it can be easily understood by all readers. As a consequence, this can result is lost grades in an academic context, or poor performance in a professional context.

Presenting graphs that are easy to understand yet contain all the relevant information is key, and in order to demonstrate how to create an amazing graph, we will be taking the following example, of the yearly price of an oil barrel since the year 2000. For most people, the data would be presented as follows:

However, this is inappropriate! 

First of all, all your figures should have a concise descriptive caption, that must also be crossed-referenced in the text; i.e., you need to refer the reader to that particular figure through the use of a figure number in the text of your report. All your figures and associated captions will then be presented in the table of figures. Note that, but using a caption, the chart title becomes redundant. I therefore always recommend NOT using a chart title, as it should feature in the caption.

Secondly, we need to scale the axis. Looking at the horizontal axis, the first year is 1998... yet no data is presented that year, the axis must therefore be adjusted to start and finish at the relevant points.

Furthermore, we need axis titles and units. What does the vertical axis represent? One can guess the price, but without certainty, it is therefore good practice to properly label your axis. In addition, what is the price in? Dollars? Yens? Euros? The axis title should be complete by the relevant units, typically between brackets.

Now looking at the data, there is no legend provided. While this is not necessarily critical since only one set of data is plotted, a legend is absolutely vital once different data sets are provided. Also note that most report will be printed in black and white, and while a blue and red line can easily be differentiated, once they become shades of grey, it is impossible to tell one from the other. This is where using markers come into place: but using distinctive markers, you can ensure you different sets of data are always discernible.

Talking about markers, you should always add markers to your lines. Indeed, this highlights what is known as the data points, namely precise points at which you have a given value. This gives the reader an idea of how reliable the line shown is: multiple closely spaced data points reveal gives the reader more confidence that some very few markers far apart.

Making those quick and simple changes instantly enhances the quality and clarity of your graph, allowing you to achieve a much more professional standard, as depicted in Figure 1 below (note the use of a cross-reference in the text to introduce the figure):

Figure 1: Yearly oil barrel price from 2000 to 2015 in USD.

And this is how you can improve you graphs, both visually and technically, to reach a professional standard of report writing and presentation.