How to learn commenting on graphs and tables the right way?

Question

I have attended many presentation where the presenter will show a graph/table in one of his/her slides, but they struggle to explain the semantics of the graph/table/results.

I think there is much more hidden in graphs/tables than young scientists can tell. Is there a way to improve this skill.

My adviser is also very strict on this, so I would like to know how to form sentences which really explain well what is being presented in the slide.

I believe a good point to start is explaining the axis and what they represent, and then comment on results. But how to improve this.

Answer 1

One problem people often have when presenting data in graphs and tables is that they often include data that is not relevant. For talks (formal or informal) I really like the process of starting with an empty graph of just the axes and explaining what the axes are and the limits and what they mean. Sometimes I then like to show idealized data from competing hypotheses so people can know what to expect without the added difficulties associated with understanding real, and potentially noisy, data.

Once people understand what the axes mean, I add data to the plot. Ideally, I start with a single data point and explain exactly what the data point means. I then add additional data points from the same "condition", possibly one at a time if they are discrete or all at once if there is some meaningful function that describes them. Once the first set of data is presented, I add on the second set. Sometimes it is helpful to remove or grey out the first set of data while you are introducing the second set of data so people can focus on just what is new. Once the second set of data is explained, bring back the first set and talk about the relationship between the two sets. This should ideally be moved to a new figure or panel to highlight the differences and similarities you want the listener to focus on.

If there is more "hidden" in figures and tables, that means it is too complicated for a talk. In manuscripts space is at a premium and you often have to have figures that tell multiple stories. In these cases the text still needs to walk you through the figure step-by-step and introduce each piece of information in the order in which you want the reader to look at it.

Answer 2

This is a very important skill to master, and a pertinent question. You are correct to first start with the description of the axes (also ensure that axis labels are legible on the slide!); this orientates the audience and will help them understand the results.

To follow on from this, I could share a couple of tips from my experience. First, make sure you understand how the slide fits in to the context of the whole presentation - what is the story you are telling? Then, ask yourself what the key point is you would like the audience to take from this slide (you can maybe get away with 2-3 points). This will guide the formatting of the figure itself, and the animation surrounding on the slides - for instance I find it useful to annotate the figure on the slide as I describe the result (for example putting a red circle around an interesting feature of the plot).

My last tip would be that the importance of practising the presentation by actually speaking it out loud (not just in your head!) cannot be understated. This is a sure way to identify areas where you are not entirely sure what to say, then you can make some more notes or write down key phrases to help you in the actual presentation.