Giving good talks - some advice

by John Conway, June 2002

You have been there, sitting in a talk, not following it, and blaming yourself for it...but could it be that
the person giving the talk just didn't know how to give a decent talk?

Preparing and delivering good talks is THE key to getting a good job in this field.

What makes a good talk good? Here is some advice which may help you in preparing a kick-ass
talk. Though the emphasis here is on conference talks, almost all of this advice holds for CDF group
meetings as well.

1. Who is your audience?

Your first task is to figure out who is going to listen to your talk, and what you want them to carry off
with them. Are you selling the excitement and the adventure, or trying to convince difficult critics you
got it right? Do the need or want nitty gritty details or just the highlights and the conclusions?

For young scientists, especially, this can be THE most difficult hurdle to overcome in giving a good
talk. You have worked for months or years, you are intimately aware of and indeed in love with all
the details, and you want to share it. In a conference talk, you must resist this temptation. And in
CDF group meetings, the details may be important but without the context they are not useful.

Start at the beginning and remind yourself why, exactly, you and your colleagues are doing the
project. Make that your first slide...then telling how you did it, and what the results are will flow

Then think again about who is actually sitting there in the audience, what their questions might be.
Are there theorists? Grad students? Ancient ("distinguished") professors? Make sure you give them
some handles to grasp your subject. On every slide the basic message of that slide should be clear.
Tell them what conclusions to draw, and then they will draw those conclusions.

When in doubt, pitch your talk as if to a first-year grad student...

2. Go high tech...mostly

Hand-written notes surrounding plots xeroxed onto plastic, handled until the finger grease smudges
are darker than the shading of the histograms...yecchhh!

Things have come a long way. Electronically produced presentations using LaTeX, Powerpoint, and
other programs, projected with an LCD projector, are much more accessible to the audience, easier
to prepare, transmit, and modify, and won't end up sliding off the table into a random pile on the floor.

Programs like Powerpoint allow you to put in lots of fancy animation, which can be used to good effect,
but which can also be annoying if used for something other than to enhance the impact of the presentation.
For example, don't make text/plots "appear" or "fly in" unless there is a good reason, such as a new
thing flying in on top of an old one.

Fonts are fun, but can also be a source of annoyance. You really, really don't want to annoy your audience,
either. Ditto for colors, and boxes, and clip art, and anything else your office mate thinks is annoying.
(I was once at a talk comparing various SUSY models, and the speaker put a photo of a supermodel
in swim suits on every slide, with little word bubbles coming out of their heads...I think this guy left the

There are indeed many tools to learn. Nearly all our plots, for example, start out as postscript, but end
up in some other form which can be imported into a graphics program. In the process, these can be
rendered illegible or worse. Make sure you understand the graphics format you are using, and the
program you are using to convert from one format to another. Spend a little time learning the finer
points of programs like Adobe Illustrator (an indispensible tool, by the way - get your boss to buy it)
and you can make compact, high-resolution, transportable plot images.


3. Make it readable!

Now we come to one of the biggest problems in our field: making decent plots. Consider the following
two plots. Which one do you want in your talk?

The bad plot

  • has unreadably small axis numbering
  • has no axis labels
  • uses "title" area as an axis label
  • title is incomprehensible
  • has colors that interfere (blue overshadows points)
  • has unnecessary box around legend
  • has legend titles with tiny text and redundant information
  • misspells "Run 2" (other misspellings include runII, Run-II, Run2)
  • uses meaningless jargon for the data point label and title


The good plot

  • has large, clear axis numbering
  • has a horozontal axis label
  • has a clear label with a legible font
  • has distinct colors that work in greyscale
  • has no unnecessary box around legend
  • has legible, concise legend titles



There are many other ways to make plots look bad. In general you should try to:

  • use large, clear axis numbering, labels and titles
  • use pastels or mixed colors rather than primary colors
  • always label your axis
  • leave off anything that it isn't adding information (get rid of drop-shadow boxes, etc.)
  • make it clear what the plot is about - don't rely on auxiliary text

In addition to making the plots readable, the TEXT must be readable too. Far too often
speakers put such small font on the slide that it is not legible. As a rule of thumb, print
out your slides, and measure the font size with a ruler. It it's less than about 4 mm, it
will not be readable from the back of the room, and should be increased.

You can't fit what you want to say if you make the font bigger? Then read the next

4. A picture is worth 1000 words

On one end of the bad talk spectrum is the kind that is all text: block after block of paragraphs,
read to you by the speaker. Then the speaker will switch to a page with just a plot on it, with no
explanatory text. Then it's back to the block paragraphs.

While this represents an extreme, it does actually happen and it's not pretty. Very often, though,
one encounters something nearly as bad: a talk where the plots are reduced to near-icon size,
lots of big, clear, full sentences describing them on the page.

Don't do that.

Your plots should take up the vast majority of the area of your slides. If it isn't about 2/3 of the
area, cut down the text and make the plots larger. In cutting down the text, pare it to the bone,
then boil the bones. Get rid of articles, verbs, adjectives...anything that is not the essence of
the information of what you are trying to say. Really, you don't need or want all those words!

Also, do you really need a CDF Run 2 logo and that of your institution on every page of your talk?
It takes up a lot of area...

Think about sitting in a talk . You want to see the plots, understand what they are saying, and
get the message from the speaker, who should be adding what's not on the slide itself. If
it's already written on the slide, you stop listening to the speaker!

5. Less is more

As noted above, you love your analysis. You have lived it for the past fourteen weeks, through
sleepless nights, hours, and meetings. You know every detail, and think it's pretty cool. Clearly
everyone wants to know all the details, right?

What your audience wants to know is why you did it, a bit about how you did it, and what the
result was and what happens next. (And whether it's the best anyone ever did!) Keep it to that,
and you will have a winning talk. Add in a bunch of boring details and they'll start looking
at the parallel session schedule for a better talk to go to.

Keep it simple and to the point!

6. Spend the time

Sure, you could go to the web, grab someone else's talk, change a few fonts here and there,
update a plot or two, and presto! You have yourself a new talk!

Properly done and researched, a talk will typically take you a MINIMUM of a factor of 40 in
time compared to the length of the delivered talk. A 30 minute talk takes at least 20 hours of
solid prep time. Think about every slide, what you re going to say, and whether this is the
best way to organize the material. Get hold of the original plots (you will need the eps to
write the proceedings!), make the plots look nice, read the CDF notes, and design the talk

No doubt you will oftentimes find yourself giving a talk which someone else from CDF gave
recently. Naturally you will use the same plots, and probably a lot of the same text and ideas.
Do your best, though, to make this your talk, and bring to it your unique perspective.

7. Practice!

Maybe it's clear to you what you mean, but is it clear to everyone else? The only way to know
before delivering your talk is to practice what you want to say in front of yourself, and then
in front of other people. You actually use different parts of your brain to speak and to listen,
and you might be surprised to hear what you are actually saying.

The only solution is to practice, practice, practice, with whoever you can get to listen. Listen
to what your practice audience says, too, and make changes, because chances are they are