Ramblings about what I encounter within the realm of the geosciences, as well as the occasional rant about nonsense.

14 September 2009

The Makings of a Talk: a Former Debater and Frequent Audience Member's Perspective

It is presentation season again. That means many people are getting their data and interpretations together in preparation for an upcoming conference. And it also means geobloggers are talking about presentations (BrianR and Tuff Cookie's entries into the subject, I will add others that I have missed as I find them). Now, I don't have as much experience as some people giving talks, but I have sat through enough talks to know what works and what doesn't work. So here I present what I think are the makings of a good talk. I have added a bit of spin to them. I was in CX debate for several years in High School, it was my first significant experience in how to set up a presentation that both educates and makes an argument. So, ever since, when I have to make a presentation I tend to go back to the model of presenting my case as if it were a CX debate (though obviously with slightly different objectives).

Introduce a Problem

First, and I can't emphasize this enough, tell the audience what the purpose of the talk is going to be about. I have sat through countless presentations where it is assumed that the audience gets all this information from the ether. Commonly, the only slide dealing with the purpose is the title slide. It is the speakers job to educate the audience, this can't be done without introducing them to the problem at hand. Now sometimes this requires very little introduction on the background (say, in a committee meeting presentation), however most times you will need to explain a little bit about what it is you are going to be talking about. Along parallel lines, think about your intended audience's background. If you are presenting at a national meeting, assume you are going to have a more general audience. If you are presenting at a regional technical session, assume you are going to have a specialized audience.


Secondly, you need to tell the audience WHY your project is important. This is, perhaps, the most important piece of a presentation. It is also almost always excluded from the talk. This is the portion of the talk that tells me why I should devote 15, 20, or 50 minutes of my time to hear what you have to say (times vary depending on setting). This isn't necessarily something that should eat up most of your time, a single slide will do nicely. In forensics (of the high-school debate variety) this would be referred to as significance. Going back to the debate analogy, many debates I have been a part of (either as a participant, or as a judge) have been won or lost on this point alone. Now this doesn't have to be paradigm shifting, it could be something as simple as nobody has looked at this area before, or nobody has applied a certain model to this setting. Or, "Jack Sprat" looked at this outcrop in 1937, but we've learned a thing or two since then so let's see if "Sprat's" interpretation works with modern understanding.

If there is no reason why you did your study, then why did you do your study? Every study has some significance behind it. Otherwise, you are just collecting facts. As Poincare once put it:
Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house.
-Henri Poincare
Or as Charles Darwin once quipped:
About thirty years ago there was much talk that geologists ought only to observe and not theorise; and I well remember some one saying that at this rate a man might as well go into a gravel-pit and count the pebbles and describe the colours. How odd it is that anyone should not see that all observation must be for or against some view if it is to be of any service!
-Charles Darwin
On a side note, "Counting Pebbles" would be an awesome name for a geoblog... or a rock band.


This is the meat of the talk, and should take the most time. How will you address this significant problem? This is where you lay out your methods, assumptions, field area, and your data. Speakers tend to not have a problem with material for this portion of the talk. The only thing I would add is make sure your data is legible. If you have scale bars (on a stratigraphic colum for instance) make sure they are readable from the back of the room. If you have a cluster diagram, make sure it is easy to distinguish one cluster of points from another. I once sat through a talk with a cluster diagram where location 1 used a blue color, location 2 used purple color, and location 3 used a purple-blue color (they were a part of a gradient color scheme). I was so focused on figuring out which point was which color, I wound up ignoring the speaker.


Solvency is your interpretation and conclusions. Does your data support your hypthesis? Does it refute your hypothesis? Does it fail to say anything about your hypothesis? Also, be sure to include what implications this has for future studies (this is where significance comes back into play). If previous studies overlooked some subtle trait, it might mean that these previous studies have to be redone.

Note that interpretation is separate from the data. This is important. If you intermix your interpretations and your data, the audience can become confused. You want them separate because, as my advisor once put it: It is one thing for a colleague to say you are wrong, it is another thing for your colleague to say you can't look at rocks correctly. Nobody should argue with your data, the rocks are the rocks, you can't change it. Your interpretation, on the other hand, is potentially falsifiable (if it wasn't, it wouldn't be science it would be dogma).

Following this general outline, in my experience at least, is a good way to propagate your point among your audience members. At the very least, they won't end up confused as to what your talk was about.

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All the Latin on this page is from my vague recollections from High School. There are mistakes in the text. I just was trying to get the point across

Between Los Alamos,NM and White Rock, NM

Between Los Alamos,NM and White Rock, NM
The photo of the travertine spring was taken in the small opening in the center of the image.

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