Visual Aids - an overview


These days it is unimaginable that a technical report or article can be written without some form of graphic display to support the text. With the advent of the digital age incorporating images in a written report is as easy as clicking the mouse a few times. Indeed, one look at a technical journal will reveal the vast array of graphics that engineers adopt when discussing their work. Click on the link to see an example of a technical paper. In this one paper you will see a wide selection of graphics: a mathematical equation, a line drawing, detailed images taken by sophisticated equipment and to a line graph. The graphics actually take up half of the article, but they are indispensable.


Before discussing in detail how to create, format, and incorporate graphics into your report or presentation, let's consider the types of graphics normally used in technical writing and their functions. Keep in mind that graphics are used to illustrate what words would say; and as we all know, "A picture is worth a thousand words". Remember, though, that this is true only if the picture is relevant and well developed.

Graphics can be used to represent the following elements in your technical writing:

  • you are using to many words to explain something
  • you are presenting trends or a lot of numerical data
  • you are doing a comparison over many categories


When you use any graphic in a report, there are several formatting requirements to keep in mind:

Titles -- Except in very special cases, any visual aid you use should have a title. The titles of all the illustrations should be numbered. For example, Figure 1, Figure 2, Table 1, Table 2 and so on. If you only have one or two illustrations, then you might want to keep the title but discard the word "Figure" and the number following it.



Example 1

Labels -- All illustrations that describe something should contain labels. That is, words and phrases with pointers that name the parts of the things being described. See Example E.

Figure 1. Percentage of Elder Houses on the High Counsel in 2001 Quarterly by Region (Alternate Title)
Keys -- Some illustrations, like bar or pie charts, have certain shadings, colors, or line styles, that have a special meaning, these should be indicated in a key. That is, an area in an unused corner of the illustration that lists and describes their meaning. See Example 1
Positioning -- You should place all illustrations just after the point where they have been discussed (cross-referenced). If this placement is not possible because of the way the text falls on the pages and the size of the illustrations, then you can put the graphic at the top of the very next page. The fact that graphics and their explanations sometimes do not fall on the same page is the reason why we need to number every illustration.
Size -- Illustrations should normally be between a-half to one-quarter of the vertical size of the page. You want them to fit on the page with the text that discusses/describes them and their main findings. Ideally, illustrations should be scattered among the text and not come all at once at the end. Also,try not to take up a whole page with one figure. This is because the reader would have to flip to and from the figure and the page where you discuss it.

NOTE: Don't use up too much time creating the perfect graphic. This course is a report writing course, not a computer graphic or arts course. And a simpler graphic works better than a really complicated one. Compare Example 1 above and Example 2 below. Which one do you think is clearer?

Example 2


Let's look at some of the more common graphics used in technical writing and presentations.


Tables are those rows and columns of numbers and, sometimes, words. They allow rapid access to information and comparison of information. Of course, tables are not necessarily the most vivid or dramatic means of showing trends or relationships between data (see the section on charts and graphs).

Uses for tables. The biggest use of tables is for numerical data. Imagine that you are comparing different models of coffee makers. All specifications, whether they are price or physical characteristics such as height, depth, length, weight, and so on are perfect for a table.

However, don't think that tables are only for numerical data. For the example above on coffee makers, you'd be providing information for the same category about each model (its cost, water capacity, supply costs, warranty terms, and so on). This is perfect for a table, and it would be made up mainly of words rather than numbers.

Table format. A table can be as simple as one row and one column of data. It can also be very complex.

At the top of each column is a column heading. This defines or identifies the contents of that column (and usually it indicates the unit of measurement, for example, percentage or kilograms). On the left edge of the table there are usually row headings. These define or identify the contents of those rows.
When rows or columns have to be grouped or subdivided, you have to create row or column subheadings. See Examples 3 and 4.


Example 3 (Format for tables with grouped or subdivided rows and columns.)

Table 4. Doubling-Dates for Carbon Dioxide Concentrations for Different Fuel Use Combinations.
Fuel 4.3% Exponential Growth Tapered Growth
Current Fuel Mix 2035 2055
All Coal After 1990 2030 2045
All Synthetics After 1990 2022 2030
All Natural Gas After 1990 2043 2075
Source: Gordon J. MacDonald. The Long-Term Impacts, 84.


Example 4

Table 2.2 Projected home use retention
of selected languages in Australia (From Clyne 1991:257)


Note the absence of any row headings in the last table. They are not necessary as the table is very simple.

Note also that in both tables the source of the information is given very clearly.

Traditionally, the title of a table is placed on top of the table or is the first row of the table. Sometimes tables can be considered as figures (that is, the same as illustrations and other graphics), and can be numbered them within the same sequence. Usually, though, tables are numbered separately from other graphics. Always start with: Table + number.

As for specific style and formatting guidelines for tables, keep these in mind (most of these guidelines were illustrated in Examples 3 & 4):





Producing tables. If you are writing about someone else's work, you can copy the information or table from an article or book. If it's a simple table without too many rows and columns, you can retype it yourself into your own document.

However, remember to state clearly where you borrowed it from. You can do this in the figure title, just below it or as a footnote!!

Most of the advanced word-processing software packages, such as MS Word or Excel have table-generating tools. You don't have to draw the lines or the other formatting details by hand anymore.

In many first drafts of technical reports, some information is presented in running-text form that could be better presented in table form. So make sure you revise your rough drafts. As you may find some material that could be transformed into a table or is best suited for tables.

Charts and graphs

Charts and graphs are another way of presenting the same data that is presented in tables. However, they are a more dramatic and interesting way. One thing to remember, though, is that graphs and charts are less accurate than tables.

Imagine the difference between a table of car registration figures for a ten-year period in Singapore and a line graph for that same data. The line graph will give a better sense of the overall trend, but not the precise number. See the examples below.

Bar Charts
Let's take another look at the table in Example 4. The data in this table lends itself perfectly well to the development of a bar chart:

Example 4

Table 2.2 Projected home use retention of selected languages in Australia (From Clyne 1991:257)


Example 5


Figure 2.3 Projected home use retention of selected languages in Australia (From Clyne 1991:257)

We can see here how a chart is visually both more appealing (mainly because of the colours) and clearer in highlighting the differences. However, it does not have the same degree of accuracy as the table. There is no way you could get the number "21,586" for Dutch from the chart; no matter how carefully you measured the last bar.

Pie Charts
If the data is shown in percentage and adds up to 100%, then a pie chart may be useful. Again, it is worth noting that it is not as accurate as a table. However, like a bar chart, it shows comparisons and divisions very clearly.

For example, if your data was as outlined in Table 4.2 below, you could present it in a pie chart (Example 6). The relative sizes are immediately visible.

However, we cannot get the actual percentage from the chart. At the same time when the percentages get very small, so do the slices of the pie and therefore they become difficult to see (look at the slices for ACT, Tasmania and N. Territory).

Table 4.2 Italy-born by state
in Australia 1991 (1991 Census, ABS)


Example 6

Figure 4.3 Italy-born by state in Australia 1991 (1991 Census, ABS)


Line Graphs
Line graphs are great for showing comparisons and trends. This is particularly true if you have more than one line in the one graph. See example 7. In this example (taken from the University of Reading's Meteorology website) monthly trends, fluctuations and differences in the minimum, average and maximum temperatures are very clear. But can you tell me (accurately) what was the maximum temperature on Wednesday, 10 July?

Example 7

Figure 4.3 Air temperature at Reading Meteorology Monitoring Station, UK, 15 June - 20 July 2002
© 2001 Department of Meteorology.

You can only say that it was about 19.6 degrees Celsius. If you are interested in accuracy then a table would be your best choice.

Producing charts and graphs. As with tables and other illustrations, there are many ways of creating charts and graphs: photocopying from other sources, generating your own with special software, and manually drawing your own. Many of the word processors have features for generating charts and graphs. You can also get special software designed specifically to produce charts and graphs. In fact, some of the examples in this section were produced using Microsoft PowerPoint.

Formatting requirements. When you create charts and diagrams, keep these requirements in mind:

Documenting graphics - indicating sources
As mentioned earlier, you are allowed to "borrow" graphics produced and published by other people. That is, you can trace, photocopy, scan, or extract subsets of data from any publication and use them in your report. However, you MUST cite your sources for graphics just as you are for the words you "borrow" from authors. Normally, this is done in the figure title of the graphics or just below the graphic or in a footnote.

Documentation  - If you borrow information or data to create a graphic, don't forget to cite the source of any information you borrowed. That is, say where you got the information from. You have to mention the person who worked so hard to get it and who deserves credit for that effort.


I hope you found this useful.





Title Key Vertical axis Horizontal axis