Data display is a way of visually presenting numerical information in the form of graphical images.  The use of text is only secondary in terms of data display results. According to Chapter 7 of Designing Visual Language there are at least three reasons to using this form of data display:

• Visual data display can be a more appealing and attractive way to present numerical information. Also some readers are more visual and would find it easier to understand and might even prefer it visually presented rather than textual.  Information can also be more engaging in visual in contrast to textual form.
• Another reason that was highlighted in this chapter is using visual display to translate highly complex data into a more accessible chart a single place where the reader can find what would be too much textual information in visual form.
• Visual data display can also be a way of creating data that can be easily accessible when looking up specific data. The chapter refers to it as a top-down perspective. It is a good way of categorizing information for the reader to use as a guide of some sort.

Jacques Bertin shows in Graphics and Graphic Information-Processing (2-23), discover things about the data by shaping them visually. At the same time, however, this freedom may also be a bit perplexing because you have to control so many design elements– spatial, graphic and textual.  Just remember that the cognate strategies you use to shape your design are driven by the rhetorical situation.  Using rhetorical situation to guide the design process will help you manage this freedom, giving you the control you need to create an effective display for your readers.

In other words Bertin is expressing the difficulties in knowing what type of visual to use in order to best convey your information. And he tries to guide us by explaining the importance of knowing the rhetorical situation. Which is defines as, the context of a rhetorical event that consists of an issue, an audience, and a set of constraints. I think it is extremely important to understand your data before you try to visualize it and present it to an audience. It is also important to try and understand your audience and how they prefer to perceive their information, which alone should guide you when formatting your presentation of data.

Being able to convey complex information in a way that can “paint a picture” is an extremely helpful tool especially when your specific audience is not necessarily very familiar with the terminology that might be used instead of a chart or a graph. This is a highly important tool to understand and utilize, because it allows your data to be organized, accessible and most of all engaging which is important to the reader.