Centre stage (a short guide to scientific presentations)

Franz Sedlacek, “Vortrag” (“The presentation”)

It’s arguably never been more important for young scientists to be able to present their data in person. Here’s TIR’s guide to preparing and delivering scientific presentations, and how to handle the questions afterwards.

There are several contexts in which one might be giving a scientific presentation – at a conference, at a seminar (external or internal), or in a group meeting. There are subtle differences in the way each ones are approached (e.g. the amount of positive/negative data will differ dramatically between external and internal presentations), but some general principles apply to all. 

A presentation should generally consist of four parts:

  1. Introduction (~20%): tell the audience what the big question is, how your project fits into that area, and what you’ve previously done or what was previously known prior to the data you’re about to present.
  2. Results (~70%): what experiments you did, what results you obtained, and how this led to the next experiment.
  3. Conclusions (~10%): summarise the results, synthesise them into a model that unifies (most of) your observations, propose future experiments.
  4. Supplementary material (variable %, theoretically unlimited): backup slides containing material that doesn’t fit in the presentation but which might be relevant for dealing with questions afterwards.

A vital element in giving a good presentation is to ensure that the audience is always aware of where in the presentation they are. If they lose orientation, they will get confused and eventually lose interest.

Title slide – include title, your name, your affiliation if necessary (group, university/institute), and the date.

Outline slide – a single slide summarising the structure of the talk. Really helpful as it provides an orientation point. You can refer back to this repeatedly during your presentation.

Background – a few slides to introduce (i) the big question that is being considered; (ii) what aspect of that big question the current project considers; (iii) what has previously been done by you and others. If you have previously presented data on the project (i.e. in an internal presentation), summarise what you showed last time.

Although the introduction is important, a very common mistake is to make the introduction too long. You are not giving a plenary lecture, so there is no need to summarise the entire field. The key thing is that the audience is primed with sufficient information to understand everything that follows in the results. You can elaborate more during the discussion afterwards.

Results should be presented in a scientifically logical order, i.e. not necessarily in the chronological order they were obtained. If you have multiple Results sections, a summary slide at the end of each section will help keep the audience abreast of where in the presentation they are.

The general rule for Results slides is “Tell them what you’re going to show them, show them the data, then tell them what they’ve seen”. In other words: (i) try and make the title of each slide summarise the conclusion, in the same way as a figure legend; (ii) then have the data that provides the support for that statement; (iii) then a brief (single-line) conclusion to ram the point home.

Always summarise your protocols. Not everybody uses the same techniques and people usually have slight (personal) variations in the way they do things.

For group meeting presentations, it is permissible to show low-quality data. Don’t abuse this privilege! Too much low-quality data and people will think you’re doing sloppy work. Always acknowledge when the data are not as good as you would like, and why if possible (e.g. “This blot is not the best and we need to re-optimise the antibody dilution; however, it does still show that…”). This does however let you demonstrate to everybody how hard you’ve been working, and lets you get feedback if you need advice. A common mistake is to leave out all the crappy data, so the audience is left with the impression that you’ve only done 1-2 blots in several months of work…

Similarly, a vital and often under-used opportunity of group meetings is to ask for help and advice if you’re not sure why things are not working as well as you would like. Use the presentation as an opportunity to pick people’s brains, as this is the only time when you have their complete and undivided attention.

For external presentations, where the time limitations are usually much greater, generally only positive data are shown. There is generally not the time available to show how you inched your way towards the publication-grade data you’re showing. No harm in mentioning that a lot of work has gone into it however, and you can retain some less polished material in the supplementals.

Summary of results – a single slide summarising the main results, preferably accompanied by thumbnail images of the data to assist recall.

Models/speculation – even if you only have a limited amount of data, it’s always worth trying to synthesise something from it. Models show that you are thinking creatively about your own data, and are a great means of clarifying your overview of the project. Remember that in presentations you are free to speculate in a way that would be inadmissible in a research article. Plus, they’re very helpful for prompting questions from the audience.

Next experiments – a summary of what you plan to do next. Acknowledge where the gaps in your story are, and how you will address them. Feel free to break this section up into short-term, immediate experiments and long-term, more ambitious ones. Can be cut if time is an issue.

Acknowledgements – list all the people that have helped. No harm being generous here. Don’t be over-the-top though – this is not the time for Oscar ceremony histrionics; just list the names and affiliations and say why they deserve acknowledgement.

Supplementary material:
This is the dumping ground for all the material that doesn’t go in the main presentation. Generally, it will consist of the following:

  1. Extra introductory slides to provide more background detail if necessary.
  2. Previous results – older data that didn’t need to go in the introduction but which may still be relevant (e.g. was shown in the last group meeting).
  3. Other data – stuff that couldn’t be included because of time constraints, preliminary data, or extra examples of things you’ve shown in Results. If someone asks you a question about it, then you already have the data to hand.

There’s no limit on the length of supplemental data, but obviously it’s not part of the main presentation so don’t invest significant time in it.

General points:
Some general points on slide style and design:

  • Plan for approximately 1 slide per minute of allotted presentation time.
  • Plan the presentation out on paper, slide by slide. It takes longer than you think to make good slides, so you want to have a sense of what each slide should look like before you start. This will also let you know how close you are to finishing.
  • Make sure that the presentation has a clear narrative arc. Results sections in particular can easily degenerate into lists of observations. With a clear, logical, thread running through the presentation you will find it easier to keep your audience engaged.
  • The smallest font size you should use is 24pt. Anything smaller will be unreadable at the back. Slide titles should be 42pt bold text. 30pt is a good size for annotation.
  • Use either Arial or Helvetica font.
  • Make sure that your slides are high-contrast and colourful so that they’re easy to read and hold attention. Black text on a white background is a good default but can sometimes hurt people’s eyes. Yellow text on a blue background provides good contrast without straining the eyes, but suffers if the beamer is weak. Use lots of bright colours in your schematics so that they stand out (green, red, pink, yellow). Outline objects if there’s not sufficient contrast with the background.
  • Make sure all your slides follow the same colour scheme. If you borrow slides from someone else, make sure they’re consistent with your style.
  • Whenever possible, ANIMATE your slides! This lets you control where the audience’s eyes are at any time. If you show all the elements of a slide simultaneously, people’s eyes will start roving around it all and not necessarily focus on the bit you’re talking about. Note that “animate” does NOT mean having flashing lights, flames, and other irritating distractions that will probably annoy – just use the “appear” and “disappear” transitions to make the material on each slide show up only when you’re referring to it.
  • When using figures from publications, acknowledge the source (e.g. “Engstler et al, 2007”).
  • Always take the time to prepare good slides. As your project progresses, you will end up recycling slides a lot so it’s worth getting them right the first time. It means a lot of work at the beginning, but it pays off at the end.
  • Make the data as large as possible, but don’t crowd the slide.
  • If you are giving the presentation in a second language and know that you speak with a strong accent, compensate for this by providing all the important information on your slides in text form.
  • Make sure you have all relevant details to hand. If you can’t remember the composition of a buffer (e.g. PEME), list it on the slide. If that leads to crowding, have the detail on a supplemental slide or written down in front of you. You should be able to provide the audience with any technical detail relating to your experiments.
  • Be aware of colour blindness! Red/green/yellow immunofluorescence overlays are a particular problem. If you have a two-colour image (red and green only), copy the red image into the blue channel to make it magenta. Areas of overlap will then show up as white pixels. Red images are generally hard to see against a black background so always make them magenta. Greyscale has the best contrast.
  • Know your audience. The content will be very different depending on whether you’re giving the presentation to specialists, generalists, or the general public. Adjust your slides accordingly.
  • As with a paper, the most important thing is to get a complete first draft together as soon as you can. You can tinker with it to your heart’s content once that first draft is there, but if you don’t have a completed presentation there’s nothing to present. Save yourself stress by getting a first version done promptly.

Presentation tips:

  • Speak slowly and clearly – whether you’re presenting in your native language or a second language, remember that not everyone in the room will be fluent. Don’t mumble. Make sure you’re loud enough to be heard at the back of the room.
  • Whenever possible, speak to the audience and make direct eye contact with as many people as possible. A common mistake is to talk to the slide with your back to the audience.
  • You’re the boss! That means you control the show. Feel free to ask questions (e.g. “Was that clear? Should I run over it again?”).
  • Keep your pointer under control. Don’t wave it around vaguely. If your hands are shaking, hold the pointer with both hands. Using a slide changer gives you the freedom of the stage.
  • Do not go over time! A presenter display is a good way of keeping track of elapsed time.
  • Personal anecdotes or jokes are good icebreakers and help show the human side of things and build rapport, but don’t overdo it. They want a presentation, not a confession.
  • Be enthusiastic! If you seem excited about your work, you’re more likely to convince others that it’s interesting. If you don’t seem interested in your own work, it’s harder convincing others to pay attention.

Dealing with questions:
Probably the hardest aspect of any scientific presentation as it’s so difficult not to take criticism personally. Some general tips are:

  • Never, ever be offended. Unfortunately, many people are unable to ask a tough question without sounding offensive, but it’s often not intended to be as aggressive if it sounds. If you overreact, you will generate a negative response in turn.
  • If you don’t understand a question, ask the person to repeat it (“I’m sorry, I didn’t understand the question. Can you repeat it please?”). If you still don’t understand it, ask them to repeat it again. If you still don’t understand it after two repetitions, summarise it yourself and answer it (“So if I understand correctly, the question is: ‘why does…?’ My answer to that would be…”).
  • Be open about the limitations of your data (“That’s a good point. I should have said…” or “You’re absolutely correct. We need to formally show that.”). On the flip side, don’t concede too much ground as it will make your story look weak.
  • If you get skewered – i.e., if someone spots something that’s a major problem – just try to escape without tying yourself in knots (“That is a really good point and it’s something we haven’t considered, no. We will have to go away and think about it”).
  • There will always, always, be someone who can think of an experiment that you haven’t done. Don’t be flustered. Just acknowledge it and move on (“We haven’t done that yet, but it’s on the list”).
  • Never, ever, make a guess. If you don’t know the answer, be open about it. If need be, make an appeal to someone who does (“I’m sorry I don’t know the answer to your question. If I may, I will pass that on to Prof. X. Prof X, is it known that…?”). That person will not necessarily know the answer either, which will make you feel better.
  • Similarly, if you speculate then always signpost it (“I don’t know the answer to that and I’m not sure if anybody does, but if I had to guess then I would say…”). This only applies to models and interpretation though. Never guess at technical details (“I’m sorry, I should know that and I don’t. I’ll find out the answer and get back to you on it”).
  • Don’t be bothered if someone asks you a question and you either covered it in the talk or if they’ve clearly misunderstood something – these are the EASIEST questions to answer, and a great opportunity to go over your story again. Always take the blame yourself, don’t accuse them of being stupid (“I’m sorry, I guess I wasn’t clear on that point. We actually covered that question in the blotting slide. Let me go back and run over it again…”).
  • If someone interrupts you to ask a question, deal with it quickly and move on. If their question concerns something that you will cover later in the presentation, tell them “Hold that thought – we will cover that in a few moments!”. NEVER, ever, jump ahead to answer their question. If you cannot answer the question quickly, provide a brief answer and suggest that you return to it during the discussion (“A brief answer would be… However, I think it’s best if we cover that in detail after the presentation – is that ok?”). The risk of interrupt questions is that you lose your rhythm and the audience loses the thread.
  • Always be polite and pleasant. Even with the assholes. Good behaviour, especially in the face of bad behaviour, will always win you friends.

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