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Introduction

As noted in the The Course Description, one of the major learning objectives of this course is to provide you rigorous training in technical communications, including oral presentations. In this course we emphasize the Assertion-Evidence presentation style because of its many advantages in terms of delivering information and audience retention, but also because it requires substantial effort on your part to produce the final product--simply dumping your written report into a PowerPoint won't get you very far.

The main resources for preparing your 176 presentations are:

  • The Assertion-Evidence presentation we went over in class (download here).
  • The Assertion-Evidence template (download here).
  • The oral presentation rubric (get from our TritonEd site).

The remainder of this wiki page summarizes the Assertion-Evidence format that we use in this class and provides a few extra resources and tips along the way.

Motivation

As an engineer you have knowledge and skills that aren't shared by most of the population, and this inherently separates groups of people into two categories, technical and non-technical. A few people have probably heard of Bernoulli's Equation, but even fewer know what a boundary layer is or why it's important, and sometimes even the basic tools like calculus that you use every day can be dismissed as unnecessary by the very people who benefit from them. Regardless of whether someone shares your technical background or would rather you shut up with your nerd talk, your role as an engineer makes it incumbent upon you to communicate your knowledge and advice to non-technical, as well as technical, audiences on a regular basis. Consider that according to the AIChE Code of Ethics, you're expected to use your knowledge and skill for the enhancement of human welfare, and along the way you're expected to

  • Formally advise your employers or clients (and consider further disclosure, if warranted) if you perceive that a consequence of your duties will adversely affect the present or future health or safety of the your colleagues or the public, and
  • Issue statements or present information only in an objective and truthful manner.

Importantly, both of these activities will require communication on your part; the most likely form of that communication will be by speaking to an audience or individual. It's therefore imperative that you convey your knowledge and advice as effectively as possible, whether the audience is technical or non-technical.

The Assertion-Evidence Style[1]

The default PowerPoint layout hasn't changed significantly since its introduction in 1987 by Robert Gaskins and Dennis Austin. That's right: I'm calling out by name the two people most responsible for the current state of affairs (but in a good-natured way[2]). As a consequence several bad habits have become embedded into our collective presentation habits, including but certainly not limited to

  • sentence fragments,
  • bulleted lists,
  • tables,
  • scientific jargon, and
  • information overload.
The Assertion-Evidence (AE) format is far more effective at communicating ideas and enabling retention, and fortunately has a very simple structure: a headline sentence is supported by visual evidence. Check out these examples compiled by Michael Alley at Penn State, each of which are excellent presentations in the assertion-evidence style by undergraduate students:
Creating Effective Slides in Engineering and Science

Creating Effective Slides in Engineering and Science

A collection of undergraduate student presentations compiled by Michael Alley at Penn State demonstrate excellent use of the AE presentation style.

There are three types of slides in the AE style: the title slide, content slides, and the conclusions slide. In all three, the headline sentence is always supported by visual evidence.

The Title Slide

A common error in the beginning of scientific talks is to create a length, jargon-filled title slide that serves to do nothing except make you feel important and make the audience feel like they're in the wrong room because they have no idea what you're talking about. Consider Figure 1:

TitleSlide poor

Figure 1. Example of a nigh-useless title slide.

Oh goody: it's the first slide and you've already introduced jargon--"AMDE"--to summarize something I didn't understand in the first place--Atmospheric Mercury Depletion Events. Instead of bowling me over with your field's specialized jargon, consider instead a title slide in the AE style (Figure 2) that orients the audience to your subject:

TitleSlide AE

Figure 2. An AE-style title slide that provides a title and visual evidence to orient the audience to your subject.

Notice the style of the presentation's title: it describes in plain language what will be discussed in the presentation, and provides visual orientation by means of an image and plot. A common mistake in presentations is to leave the title slide too soon by stating in an almost obligatory way, "here is my title and here is my name and the names of my collaborators." Instead, force yourself to spend more time with this slide and stay there until the audience, through your words and the visual evidence you have supplied, has a chance to comprehend the key details of the title, and--by extension--the topic of your presentation.

Sometimes the Title Slide will be followed by a Mapping Slide if the talk is expected to be lengthy or the connection between sections deserves special emphasis. Most of your talks for 176 won't require such a slide but the AE style nevertheless includes guidelines for creating such a slide; download the Presentation Template or the AE Introduction slides for examples.

Content Slides

Before introducing the AE Content Slide style, consider the slide regarding analog-to-digital signal conversion shown in Figure 3:

ContentSlide poor-0

Figure 3. An example of PowerPoint's default slide design that emphasizes a topic-subtopic structure.

The default PowerPoint layout used here, sometimes called the Topic-Subtopic structure, is based on three fundamentally weak propositions:

  1. Misconception: Short phrases and/or "phrase headlines" are more memorable or understandable than sentences. Reality: Audiences are easily distracted; simple "phrase headlines" offer the distracted audience member no method to re-orient themselves if they zone out for a moment. Short phrases are typically incomprehensible unless the audience member can recall exactly what the speaker said in reference to that point.
  2. Misconception: Audiences can read text and listen to the speaker simultaneously. Reality: The same part of your brain that interprets written words also interprets spoken words. Translation: the more words you put on your slides, the more opportunities there are for the audience to stop paying attention to what you're saying. Avoid including text that would require reading more than about 20 words per minute (add up the number of words on your slide and divide by the time you spend on it).
  3. Misconception: Bulleted lists are easy to follow. Reality: Not only do bulleted lists limit the space for graphics, there is no evidence that such lists, even with their seeming ability to connect topics, enable the audience to comprehend or remember any of the details from the talk.

Similarly, some presenters compound the situation by adding graphics as in Figure 4 to produce a sort of hybrid abomination, the Topic-Subtopic+Graphic slide:

ContentSlide VeryPoor

Figure 4. An abomination: the Topic-Subtopic+Graphic slide. Don't waste the money it costs to run a projector just to show a slide like this.

Unfortunately, adding graphics to the Topic-Subtopic structure only adds to the amount of information the audience must assimilate, often leading to information overload. Consider what might go through an audience member's mind upon seeing Figure 4:

  • What's that title mean? What's a digital acquisition system, and how do I sample it?
  • I'm going to try to read everything on there before you get to it so I know what you're saying and where you're going.
  • Crap, you're saying something that's not on the slide! What did you say? I was reading; come back!
  • Oh no, now you're reading everything verbatim and I already read it. BORING.
  • What is that wavy line? Should it be the dotted one or are they not related?
  • That computer thing looks complicated.
  • Look, a bird!
  • Uh oh, I'm lost. What's she talking about now? Oh right, the signal sample rate. How is that related to the sinusoidal shape again? I forget.

How can we keep the attention of the audience? How can we allow them to re-orient themselves when their attention inevitably strays? We capitalize on the structure implied by the style, "Assertion-Evidence": an assertion is made using a full sentence headline, and this assertion is supported by visual evidence. Consider the AE content slide in Figure 5 for the same digital acquisition slide.

ContentSlide AE

Figure 5. An assertion-evidence slide for the digital acquisition system provides a straightforward statement (the assertion) supported by graphics (evidence).

With almost no explanation you can probably understand the message of this slide because you can read the full-sentence headline assertion and you can follow the visual evidence.

This is not to say that you should dumb everything down so that the audience no longer needs to listen to what you're saying. In fact, in most scientific presentations, you're going to have to explain why the evidence you've supplied is indeed evidence. In many instances, your evidence will be a plot of one variable against another and then you're going to have to explain why the relationship is important and what aspect of the plot is the evidence of your assertion. In Figure 5, for instance, you'd have to explain that the entire graphic constitutes the "digital acquisition system" and then explain the important points of the assertion by highlighting--verbally or graphically--what each graphic is supposed to imply.

There are several variations on the AE style for different evidence styles--figures, equations, call-outs--that you can review in the Presentation Template or AE Introduction slides.

The Conclusions Slide

If you've seen a fair number of presentations then you've undoubtedly come across a final slide similar to the one in Figure 6.

Conc poor

Figure 6. A common example of a Conclusions or Questions slide.

Put simply, this is a waste of a slide: this slide tends to be displayed the longest (as you answer questions) yet it has no information and provides no way for the audience to recall what the purpose of your talk was. Instead, why not put the last slide to work by including a helpful summary? Of course, we again use the assertion-evidence style; an example is provided in Figure 7.

Conc AE

Figure 7. A combined conclusion and "questions" slide in the AE style combines a summary statement and evidence to support it.

In this way the most important point--the "take-home message," if you will--can be emphasized again, or even for the first time if your presentation time is severely limited (as it is in our course). Importantly, your final slide should have two characteristics:

  • The final slide's assertion should begin with the phrase "In summary..." or "In conclusion..." to inform the audience that you've reached the end of the talk.
  • Don't put in any more slides after the conclusion slide! You just told them the talk is about over; don't pull the rug out from under them and start presenting more content. This will obscure or detract from the importance of your take-home message.

Finally, there is no reason for an entire slide just to ask for questions; a simple "Questions?" at the bottom is sufficient because you're undoubtedly going to inform the audience that it's time for questions.

Formatting Guidelines

Style

To create an AE slide, keep to the following guidelines[3]:

  1. Begin each body slide with a sentence (assertion) headline that is left justified and no more than two lines.
  2. Support the assertion headline with visual evidence (photographs, drawings, graphs, films, or words and equation arranged visually) and avoid bullet lists.
  3. In the body of the slide, use words only when necessary! Design your slides so that the audience reads no more than 20 words per minute.

These three points might seem simple on the surface--and they are--but you'll find that it requires significant effort to compress complex ideas into one or two slides structured in this way, especially when you've only got 5 minutes to give your presentation.

Typography

Again, three simple guidelines:

  1. Use a bold, sans serif typeface such as Helvetica or Calibri.
  2. Use 28 pt type for the headline, 18-24 pt type for the body, and 12-14 (not bold) for callouts and other labels.
  3. Avoid setting text in all caps, italics, or with underline.

Layout

Here's the magic three again:

  1. Keep blocks of text, especially the headlines, to no more than two lines.
  2. Limit slide content to two, three, or (at most) four evidence items.
  3. Use small margins on the sides to allow sufficient whitespace between elements (e.g., leave at least half an inch of whitespace below the headline and between figures).

To these three I would add a fourth of my own: use a 4:3 aspect ratio rather than 16:9. Most projectors will letterbox 16:9 to become 4:3 by compressing your text and introducing ugly bars on the sides.

Citations

If you use images or graphics from an outside source then you also need to include a citation. The citation should be included near the graphic (below it, for example) and can be in one of the following simplified formats:

  • Journal articles or books: [Author, Year]. Example: [Perry's Handbook, 2008].
  • Websites: [URL (short)]. Example: [ucsd-ceng-176.wikia.com].

References

  1. All of the material below follows from the work of Michael Alley at Penn State. You can view his website at Scientific Presentations: The Assertion-Evidence Approach.
  2. Please don't sue me, Robert Gaskins and Dennis Austin.
  3. Checklist for Assertion-Evidence Slides. http://www.writing.engr.psu.edu/AE_checklist.pdf (accessed 7 Jan 2016).
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