Visual signalling
In turning to consider the use of tables, graphs, diagrams and other illustrations in the presentation of information, we are not changing our topic. Our subject is still clear communication, and we are still discussing how to make precise, manageable statements using language. Words, graphs and drawings are all visual patterns used to symbolise or represent meaning. In both graphic statements and verbal statements, we use a variety of hieroglyphics—dots, dashes, and other marks on paper—as symbols to carry information. Words, after all, are made up of letters which are composed of combinations of lines and circles; for example, the difference between ‘o’, ‘p’, ‘d’, and ‘b’ lies only in the positioning of the line tangential to the circle. So words and drawings are not conflicting or competing modes of expression. They are, at most, extremes on a continuum, with words at one end making minimum use of the visual appearance of the signals, and with drawings and graphic presentations at the other end making maximum use of the visual appearance of the signals.
In earlier chapters, we have discussed how statements in words often cause difficulty for receivers because they contain unfamiliar vocabulary or signals, because they are too long and complex, or because they require the reader to hold in mind too many inter-related clauses and conditions. Visual statements can be difficult for the receiver for similar reasons: they may contain vocabulary or signals with which the reader is unfamiliar; they may be too long or too complex; they may contain too many inter-related items and conditions for the reader to absorb. So, just as writers must be skilful in selecting words and sentence structures from the verbal code, they must be equally skilful in selecting and handling the elements from the visual code.
Thinking about the task
All that we have said in earlier chapters about tactics for selecting and handling information applies equally to the choice of visual techniques. As always, aim
and audience are the governing factors in this choice, and it is especially important to consider two questions:
• What is the precise function of the table or illustration?
• Will the readers of the paper receive this information more readily in verbal or in numerical/visual form?
We have argued earlier that the way a text is organized and laid out, and the rate at which information should be ‘unloaded’ or packed into our pages, must be varied according to the function of the text. In a dictionary or a parts list, it is effective to pack together a great deal of information tightly and economically, because these texts are designed for reference, for scrutiny and cross-checking of particular items. We must make it easy for ‘readers’ to find their way into and around the assembled information, but we do not have to construct a coherent discourse; the entries are not statements in a connected argument. Tactics of selection and organization are different from those used in a report or an instruction sheet.
In just the same way, tactics in using tables and graphic techniques must be related to the precise function of the document as a whole and of the visual items in particular. Distinguish between tables and charts that are to be used for reference, as stores of classified and juxtaposed information, and visual statements that are to be used to make a point in an explanation or argument. Tables and drawings designed as reference material (such as wall-charts or timetables) can be packed tightly in the equivalent of dictionary or parts-list form. They are usually best separated from the main text of a report or paper so that they are not an obstacle to the readers’ smooth progress through the argument. Tables and drawings that are designed to make a point as part of an argument should have simple structures and carefully judged information-loads. They should be placed as close as is physically possible to the point in the prose text at which you want readers to take in the information they provide. For example, Fig. 10.1 shows a very detailed chart, providing a mass of information about the enthalpy of methane for reference and for scrutiny of detail. In most circumstances, it would distract the reader if it were part of the text, and it would be best placed in an appendix. Fig. 10.2 shows a specially drawn graph, based on the same information as Fig. 10.1; but it is a simpler statement designed to make one particular point. It was placed within the prose text of a report, close to the point in the argument at which the visual point was needed.
A practical tip: abstractions of information like this can often be made simply by putting tracing paper over a complicated original and inking in the significant lines. The traced outline can then be photocopied (perhaps even reduced) and included conveniently within a typewritten report or paper.
The second important question—will the readers receive the information more easily in verbal or in numerical/visual form—is of particular concern to writers who must communicate to specialists from a wide range of backgrounds. It is
well established that readers will take more information more rapidly from documents if they know what to expect from the document and where in the document to look for it. It is also well established that some people are by nature and training more inclined to be ‘verbalizers’ and others are more inclined to be
‘visualizers’. Some readers will find it easier to assimilate the verbal statement,
‘Output falls to half within the first hour, to a quarter within the next hour, and then stabilises at one tenth for the remainder of the run’; other readers will absorb that information more rapidly if they are shown a simple graph that shows output plotted against time.
Fig. 10.1 A detailed graph for reference, best placed in an appendix (reproduced by permission of Philips Components).
In writing for engineering and scientific readers, you will probably decide that they will usually be helped by the use of tables and graphic presentation techniques; but which technique still requires careful thought. Readers who like block diagrams may be bemused by complex drawings of electronic circuits. In debates with engineers and scientists about the relative effectiveness of different algorithm layouts (discussed in Chapter 6), we have been surprised to find how powerful is the influence of ‘what they are used to’.
The resources and techniques available to the writer
In this chapter, we shall discuss only the best use of resources and techniques usually available to writers who have by themselves to produce internal reports and papers, articles for journals, instruction sheets and other similar documents.
This is not a chapter for professional illustrators. If you are fortunate enough to have access to experts who can produce exploded drawings or use airbrush techniques, always involve them as early as possible in your planning and preparation for a report or paper. But most engineers and scientists have to rely on their own resources to produce the graphic presentation of their data. What is the best way of doing this?
Fig. 10.2 A summary graph, based on Fig. 10.1, designed to make a point in the argument, best placed in the text of the document (reproduced by permission of Philips Components).
First, review the ‘language’ elements available. The main symbols in visual presentation are:
• numbers (used mainly in tables);
• words (used in tables, algorithms, or flow charts);
• lines (used in graphs and drawings to symbolise paths, links, a lapse of time;
• shapes (used in symbolic charts, drawing and photographs).
These symbols constitute the equivalent of the verbal Vocabulary’. This vocabulary is put together into the visual equivalent of sentences and paragraphs, and as in your choice of verbal ‘style’, it is vital to:
• consider carefully the length and complexity of the statements you ask your reader to digest;
• be sure to conform to conventions of ‘word order’;
• avoid the visual equivalent of wordiness and waffle;
• control the use of jargon.
In visual signalling, you also have available important cues that you cannot use in verbal signalling:
• spatial cues (alignment in columns and rows, grouping);
• typographic cues (size, design, and weight of type);
• colour cues (shading, colouring, colour of paper as well as of print);
• ruling (use of lines not as symbols in themselves but as a framework to separate, group and relate information);
• use of ‘white space’ to group or emphasize items of information.
Perhaps the greatest advantage of visual presentation is that it is possible to represent three dimensions. Prose restricts information to a one-dimensional linear sequence: visual presentation enables you to show shapes, to show activities going on in parallel, to show movement in varying directions. Your reader can take in all these things ‘at a glance’, because the human eye can use a span of awareness much wider when looking at visual presentations than when looking at words (focus on any word in this sentence, and notice how much of the surrounding text you can see without changing your point of focus). By presenting information in tables or in graphic forms, you can often make much more efficient use of your readers’ perceptual abilities than by presenting information in prose.
But remember that perception and comprehension are not the same. Your readers must not only perceive your visual presentations but also understand them. So beware of complication and overloading. Give readers the minimum data needed to make your points, not the maximum data available to justify your
existence. And make your visual statements self-sufficient, so that readers can comprehend them without continuous cross-reference to the prose text.
Just as it is desirable to coin a new sentence each time you want to say something, it is wise to try to produce a fresh illustration each time you decide you want to make a visual statement. Automatic re-use of pre-packed words and phrases frequently produces only approximations to the intended meaning of a statement: likewise, apparently time-saving (and thought-saving!) use of ready-made graphs or photographs frequently presents only an approximation to the point intended. As you work at communication tasks, you will constantly be tempted to trade-off efficiency against convenience. Often, you will be able to use existing visual material very effectively; but sometimes you may be tempted to write a text that fits the available visual material rather than to take extra trouble to produce visual material to suit your text. Resist this temptation.
The great advantage of using visual presentations is that they give all readers the same visual image to look at. But notice that we are not saying that readers will all see the same thing: each illustration must have a caption or heading telling readers what you want them to see in the illustration. Imagine two identical pictures of a boy kicking a ball along the pavement of a busy suburban street.
One caption reads: ‘Road-safety training teaches children to stay safely on the pavement’. The other caption reads: ‘We need parks to keep our children away from dangerous roads’. Readers see different points made by the same picture in the two illustrations. You might be entertained by taking any drawing or photograph designed for inclusion in a report without its caption, and asking your colleagues to tell you not only what it shows but also what point it is making about its content. We suspect you will rarely get a clear or unanimous response.
Tables
Tables give a systematic and orderly arrangement of items of information.
Tabular layout has the particular virtue of juxtaposing items in two dimensions for easy comparison and contrast. Tables eliminate tedious repetition of words, phrases and sentence patterns that can instead be put at the tops of columns or at the sides of rows in the table. Although tables do not make much impact by visual display, it is possible, by careful arrangements, to emphasize and highlight particular items or groups of information.
There are several ways of arranging information within a table and no one way is always the best. As usual, we must return to our basic questions: what are we trying to achieve with this table? What is the required emphasis? For whom are we presenting the information? What are the interests and needs of those readers?
Tables can be organized with the information in numerical order, in alphabetical order or in an order which groups items according to common features or common values. Normally, however, readers expect the elements or
entities which are being compared to be grouped or listed vertically, and to find variables, qualities or performance details listed horizontally. Readers expect to move from known material on the left to new information on the right; known (or base) information should therefore appear on the left, with explanatory, conversion, or derived material on the right.
We find it helpful to distinguish two broad types of tables: dependent tables and independent tables. A dependent table is placed in the text and is an integral part of the prose statement. It continues the sentence or paragraph in just the same way as a mathematical or chemical equation that is included in a sentence, and it needs no title or caption because it is a continuous part of the text. It follows that it must be restricted to a small amount of information, probably a maximum of two or three columns and rows, a dozen or so numbers in all. An example of a dependent table is shown in Fig. 10.3. The reader can read through this table as a continuation of the sentence that it completes.
The table shown in Fig. 10.4 is too large to be presented as a dependent table.
It is not reasonable to expect readers to absorb the information presented within the table as though they were simply continuing to read through the paragraph.
The amount of information presented in that table requires readers to stop and reflect on the arrangement of facts. Since the writer wanted the readers to absorb this information at this point in the account, it should be left in the place that it occupies on the page; but it would have been wiser to have separated it from the text more clearly by surrounding it with white space, and by giving it a table number and a caption. Even more effective, probably, would have been to make prose summaries of the significant points that emerge from the data and to have put the full table in an appendix.
An independent table may be placed physically within the text—be surrounded by it—but should be clearly distinguished from it. In an independent table, you are inviting your readers to look at a visual display of the information separate from their reading of the text; the amount of information being presented will require a conscious step by the reader from the text to the table and back again. Minimize the size of that step if you can, by placing the table as near as possible to the text that discusses it (often this will be difficult in a typescript report and it may be necessary to collect the independent tables at the end of the report). Clear captions focusing the readers’ attention on the significant facts or inferences that you want them to see are also important.
Ruling
The design of the ruling in independent tables presents choices: an open design, a semi-closed design or a closed design. An open design is one which has no vertical or horizontal rulings in it at all. A semi-closed design has just some vertical lines and/or some horizontal lines. A closed design has a complete array of both vertical and horizontal lines separating virtually all elements from all others.
Consider the examples in Figs. 10.5, 10.6 and 10.7. Which of these helps you to see most readily the information that the writer is trying to present with particular emphasis? Even if you do not know what information the writer wants to emphasize, it is possible to sense the difference of impact of the various ways of ruling a table. Most readers find an open table (Fig. 10.5) is confusing, giving too little help to the eye. A fully closed table (Fig. 10.7) is also difficult to use because the apparatus of lines seems to overwhelm the information that is being presented. Most readers prefer a semi-closed design (Fig. 10.6), with some horizontal and/or some vertical lines to help signify the importance of the piece of data.
Are vertical lines or horizontal lines preferable in semi-closed tables? There can be no over-all rule, because the lines in the tables may be doing two separate things. They may be helping the readers’ eyes with the simple business of seeing the figures in the table, and they may be stressing the significance of particular groupings. They may be guiding the eye across the page or down. Most readers are accustomed to looking up and down columns of figures without too much difficulty, provided the figures are carefully aligned by the typist. They need more help when they have to compare figures in horizontal rows. That might seem to suggest that in semi-closed tables, the normal use of lines should be horizontal.
But you must also take account of the second function of ruling within a table.
That function is to stress the significance of particular groupings. It may be that you wish to stress groupings that are horizontal or vertical. In those They were anxious to know our plans and how we saw growth, particularly with respect to increasing governmental pressure, towards better and improved run characteristics in products
2. EUROPEAN PRODUCTION REQUIREMENTS
The forecast provided by Production Planning, London was tabled as follows:
Requirement (Mt) 1988 1989 1990
Min 1.9 3.5 4.8
Max 2.9 5.4 7.2
It was explained that these are min-max numbers and that the use of the average would be most realistic. With these numbers plus US requirements, the present plant design capable of 2.5–3.0 Mt with small-scale de-bottlenecking, would be outstripped in 1989. Thus, a European site would provide the added volume plus provide the safety of a second source.
Exploratory discussions on the concept of buying product in Europe and on stock procedures at the sites was accepted without commitment for further study. Technology was via denitrogenation, by the route:
NaCl+C2H6N2 —— 22H4Cl+NaN2+H2O
This process yields a serious loss of nitrogen via salts and it is a very important economic facet of this process that any nitrogen loss is fully recovered. Initially, the raw material is transported to site in single-load tankers to
Fig. 10.3 A summary table, brief enough to be included in the text.
circumstances you have to weigh up whether readers will need more help in seeing the significance of groups, or more help simply in following the rows of
circumstances you have to weigh up whether readers will need more help in seeing the significance of groups, or more help simply in following the rows of