Displaying Data Clearly

So…what makes a good data slide?  There are many ways to make good data slides, and many, many, ways to make really terrible ones.  If you start reading articles and talking with people about it, you’ll get some contradictory advice –  with trial and error, you’ll figure out what works for your own style.  Here are my favorite tips:

Make sure your slides are accessible to people with colorblindness.  This will help you avoid seriously embarassing yourself in public, and it will also make your visuals clearer to everyone in your audience.  I’ve written up a separate page of tips on choosing and using colors well.

What is the meaning of your data?  Step away from the graphs and stats for a minute and figure out what your key point is.  Ask yourself what you want your audience to remember about this data – and then you can design a slide to convey it.

Each slide should make ONE key point.  Figures and tables designed for printed papers are extremely dense in order to save space.  As a result, the reader often needs to spend several minutes disentangling multiple layers of information.  A presentation is a totally different format, and data slides need to be designed so your audience can understand them easily.  If your data slide is trying to convey multiple points, split it up into multiple slides.

Consider using a full sentence for the title of your slide to state that key point.  This doesn’t work in all cases, but I’ve seen it used extremely well.  Instead of just labeling the slide “Soil Moisture,” your audience will immediately know what it’s about if your title says “Diversity increases soil moisture.”

Simplify, simplify, simplify.  Every element on the slide should help to convey that one key point.  If it doesn’t, seriously consider deleting it.  Start with a blank PowerPoint slide, not a cutesy template, and don’t put on extraneous logos, icons, etc.

 Be seen.  Now that you’ve gotten the extraneous stuff off the screen, you should have plenty of room to make everything on the screen big enough to be seen.  Some suggest a 20pt minimum for all words; I like to go with 24pt or larger if possible.  Step back from the screen and check.

Make it quick and easy for your audience to grasp.  Use full words instead of cryptic abbreviations (e.g. site names, treatments) if space permits.  Label your axes with what they’re talking about – “m/s” isn’t nearly as informative as “Seed dispersal velocity (m/s).”  Replace legends with labels directly on the figure whenever possible (especially helpful for line graphs!), so your audience doesn’t have to look back and forth several times to match things up.

Double-check that your slide conveys that one key point.  It can be easy to get off-track when working through all the details, so double-check at the end.  If you can corner a willing friend, just show them the data slide without explanation and ask them what they think it means.

Presenting your data:  OK, now you’ve got it looking all clear and pretty and everything — don’t overlook your role as the presenter!  As soon as a data slide goes up, tell your audience what they’re looking at.  “Here we’re showing seed production for our three species throughout the year.”  “This is a plot of soil nitrogen on the X axis, versus ant populations on the Y axis.  Open circles are the unfenced plots, and black squares are the fenced herbivore-exclusion plots.”

Putting up the data slide without telling your audience what it is will result in your audience tuning you out for a minute while they read your axes and try to puzzle it out for themselves.

Also tell them the point.  Remember that data are not self-explanatory!   “Ant populations increase with higher soil nitrogen in the control plots, but when we exclude herbivores that effect goes away entirely.”

Laser pointers encourage extremely poor presentation technique (and the red ones are invisible to many color-blind people).  Green ones are universally visible and can sometimes be used well, but I recommend against them.  Poor lighting setup, all too common in lecture/presentation rooms, can easily render your laser dot hard to see.  Physically going to the screen and pointing at things (use a pointer or stick if it’s a big screen) is easier for the audience to follow than a disembodied dot briefly appearing on the screen, and it also forces you to change your rhythm and focus in subtle but helpful ways.  Putting arrows/circles/etc onto the slide is the another good technique to show your audience what you want them to focus on (they’re more visible than laser pointing, and they stay around longer).  Remember NOT to just gesture briefly and say “Over here” or “This one.”  Some of your audience will be looking away at that moment — like those interested enough to be taking notes! — and they won’t have any clue what you’re talking about.  Whatever method you use to point/highlight, refer to it by something meaningful, like “In the early data,” or “The drop-off at high velocities,” or “The nitrification pathway,” etc.  It also helps the ideas flow and connect better for your audience.

Oh, and don’t turn your back to the audience for more than a moment at a time.  Some presenters do great until they get to a data slide, and then they spend the next two minutes turned away from the audience and talking to the screen.


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