Oral presentations almost always present information and ideas that are new to the audience. Graphics are great help in making these ideas clear and understandable.Now whatshould you present graphically? The most prevalent types of graphics answer the following questions:
- "How is the speech organized?"
- "How does it look?"
- "How do the data look?"
It is useful to present a graphic introducing your team and your topic just in case no one has introduced you or someone has introduced you poorly. Show the audience the title of your speech, your name and role, your department and college or company, and a date.It is useful both for the speaker and the audience to present an organizational plan of an oral presentation. But present this in phrase, topic, or note form, not in sentence form. Start with a forecast listing the topics to be discussed. Then list the sub-topics to be discussed under each topic as you come to the topic itself. Finally, in conclusion list the topics that you have now covered. (See Make the Organization Obvious.) With such graphics, the speaker needs no other notes.
Technical speeches often deal with things with which the audience is unfamiliar, for example, unusual or new software interfaces or the floor plan for a proposed new library or the exterior of a building with similar architecture.Now should you show it with a photograph, or with a sketch, or with a diagram?
Photographs
Photographs are easy to take, but expensive to turn into transparencies or slides. Moreover, a photograph tends to be unselective, it will show all the details whether they are relevant or not. So the speaker should first ask her1self, "Is it the appearance of the thing that is important, or is it the principles of its operation?"Some speakers love to show you pictures of their apparatus even if all the audience can see are instrument panels with knobs and dials and a title underneath like, "Figure 6. Scanning Densitometer". This is not likely to be informative. The audience would prefer to understand the principles upon which the apparatus works.
Screen Shots
Screen shots are essentially photographs of a computer screen. They are invaluable when you are presenting a proposed interface or critiquing a current one. When displaying screen shots, be aware that it will be difficult for your audience to follow your comments if they are not focused on the same screen element you are. Even if you say "Notice the bloppity button in the right corner..", many in your audience will not follow you. To combat this problem, type large callouts with arrows on top, or better to the side, of the screen shot. You can also use a laser pointer on complicated screens to change the area of focus and remind listeners of the area of focus.Sketches or Diagrams
If it is the principles of operation that are important, then a sketch or diagram may be far more effective. That is why the specifications for military manuals recommend the use of sketches in place of photos. The nonessential features can be eliminated.But one warning about sketches and diagrams. They should not be so abstract as to be incomprehensible. R.L. Gregory in another book, The Intelligent Eye (pg. 155-l66) points out that the original diagrams of electrical circuits, such as the Wheatstone bridge, were literal representations of the actual wires, resistors, galvanometers, and switches. But little by little abstract symbols began to replace these representations--a wiggly line, for example, became the symbol for a resistor--until today a modern circuit diagram with its triangles to represent And Gates and little circles to represent Inverters is probably incomprehensible to anyone but a computer hardware designer .
Tables
If you have a rather small data set, you might heed Tufte's advice:"Tables usually outperform graphics in reporting on small data sets of 20 numbers or less. The special power of graphics comes in the display of large data sets." Pg. 56Tables should be easy to design, but I have often seen some very awkward ones. So I suggest these rules of layout.1. Provide a title to tell the audience what the table indicates and what the data base is.
A column of labels and numbers may mean nothing at all to the audience. They need to be told what is being presented. Moreover, they need to know what data base is being used. In the illustrations which follow two separate data bases will be used; one, all students enrolled in the Fall Term 1982 at the University of Michigan; the second, only the students graduating in May 1982 from the University. Unless these data bases are presented in the table title, the differences in the data will be confusing.2. Arrange the data in the table according to the purpose in mind.
Tables are used to present an array of data in a meaningful form. It is rather like sorting a deck of cards into separate piles according to distinctive features -- into black and red cards, or into suits. As an illustration, we will use data representing students at the University of Michigan.
Table 1. Students enrolled at the University of Michigan--Ann Arbor, Fall Term, 1982 . (Source: University Registrar's Office)
Architecture 505 Art 597 Business Administration 2,258 Dentistry 774 Education 1,184 Engineering 5,518 Law 1,145 Library Science 210 Literature, Science, and the Arts 16,411 Medicine 1,761 Music 827 Natural Resources 718 Nursing 744 Pharmacy 246 Public Health 633 Social Work 560 Intercollegiate Graduate Programs--- 768 --------- TOTAL 34,859 However, if we are more interested in the relative numbers enrolled in each of the schools and colleges, we might better arrange the data in either ascending or descending order by number enrolled, as in Table 2.
Table 2. Students enrolled at the University of Michigan--Ann Arbor, Fall Term, 1982 . (Source: University Registrar's Office)
| Literature, Science, and the Arts | 16,411 | |
| Engineering | 5,518 | |
| Business Administration | 2,258 | |
| Medicine | 1,761 | |
| Education | 1,184 | |
| Law | 1,145 | |
| Music | 827 | |
| Dentistry | 774 | |
| Intercollegiate Graduate Programs--- | 768 | |
| Nursing | 744 | |
| Natural Resources | 718 | |
| Public Health | 633 | |
| Art | 597 | |
| Social Work | 560 | |
| Architecture | 505 | |
| Pharmacy | 246 | |
| Library Science | 210 | |
| ------------------ | TOTAL | 34,859 |
3. Subdivide the data base only twice for a single table.
If we try to subdivide the data base three times, we end up with 8 columns of data -- too many to digest easily. In Tables 1 and 2 above the data base has been subdivided once,into units. In Table 3 a different data base has been subdivided twice, once into units, then a second time into status.Table 3. Students graduating from the University of Michigan-Ann Arbor in May 1982 by unit and status. (Source: University Diploma Office)
Unit Undergraduate Graduate Total Literature, Science, and the Arts- 1,959 230 2,189 Business Administration 0 660 660 Engineering 434 177 611 Law 0 320 320 Education 147 95 242 Medicine 0 228 228 Nursing 180 48 228 etc. If we try to subdivide the data base one more time --making threesubdivisions -- here is what we get:
Table 4. Students graduating from the University of Michigan--Ann Arbor in May 1982 by unit, status, and sex. (Source: University Diploma Office)
Undergraduate Graduate Total Unit Men Women Men Women Men Women Total Lit. Sci., Arts 1,077 882 126 104 1,203 986 2,189 Business Admin. 0 0 396 264 396 264 660 Engineering 303 131 123 54 426 185 611 Law 0 0 224 96 224 96 320 Education 59 88 48 47 107 135 242 Medicine 0 0 171 57 171 57 228 Nursing 9 171 8 40 17 211 228 etc. Table 4 is simply not easy to digest. (Partly, because my HTML skills are less than stellar ;-) ) It might be useful as reference material to be read later, but if needed, it would probably be better represented by a bar chart.
Line and Bar Charts
Graphs for speeches must be simple and easy to understand. For this reason, I offer the following suggestions:Pie Charts
- Limit the number of lines or bars on a graph to three or four. More lines or bars tend to be confusing.
- If possible, label the vertical axis of a graph so that it can be read horizontally.
- Label each line or bar on a graph on the line or bar itself or close by. Don't make the audience try to find the meaning of the shading in a separate key off to the side.
- Use distinct shading choices.
- Avoid competing titles. One title is sufficient.
- Skip the three-dimensional effect for simple data sets. If the third dimension has no data purpose, you are better off without it.
- Don't let the graphing tool make design decisions for you. Make conscious choices based on good design principles. (Most MS Excel defaults can be easily modified and vastly improved with minimal effort.)
Pie charts have been widely used in advertisements for spreadsheet computer software programs and in popular publications, such as USA Today. Pie charts often have the effect of making the content appear pseudoscientific, and people concerned with precise data tend to abhor them as you can see form the following Tufte quote."Tables are clearly the best way to show exact numerical values, although entries can also be arranged in a semi-graphical form. Tables are preferable to graphics for many small data sets. A table is nearly always better than a dumb pie chart: the only worse design than a pie chart is several of them, for then the viewer is asked to compare quantities located in spatial disarray both within and between pies .... Given their low data-density and failure to order numbers along a visual dimension, pie charts should never be used." Tufte (Pg. 178)
Keep your graphics simple, brief, and clear.Limit the text on your graphics to phrases, not sentences or paragraphs. And limit the number of phrases to three or four. Remember, the audience can read faster than you can talk, so while you are talking about the top line of text, they may well be reading the bottom line and paying no attention to you.
Remember to keep the text at an acceptable size and use strong contrasts between the text and background and between items in a comparison chart.
Turn off the projector or remove your display and talk directly to the audience when you are finished. Don't leave the audience staring at your last graphic after you are all done.
The overhead projector is difficult for every speaker You must stand near it in order to change transparencies or acetates, but your own body will be in the way of the view on the screen for part of the audience. Moreover, the mirror on the vertical stalk tends to hide part of the image on the screen.If you can, stand by the side of the screen. Use a pointer to indicate items on the screen to which you want to call attention.
However, if you have several displays to present in succession, it is better to stand by the projector so that you can handle them quickly without interrupting your speech.