Over the last couple of weeks we've concentrated on data visualisation, emphasising the importance of clear, unfussy methods which don't obscure the story of the data. A good figure can be very powerful, but may not be enough on its own to convey a message. In particular, if you are giving a presentation in person, I suggest that projecting a succession of figures onto a screen - no matter how well put together they are - is not the best way to get your point across.

Memorable images are key in giving a good presentation - even if you have 10 killer figures that you'd like to present to your audience, run through them all on Powerpoint and their power will quickly wither away to naught as your audience suffers information overload. They spend so much time squinting at the screen, it really doesn't matter what you're saying as they've stopped listening.

A better idea: select the very best two or three figures which support your argument and mix them up with some visual aids which, while not carrying the same intellectual weight as your carefully compiled data, are just as important in making sure your ideas stick in the mind of your audience.

Let's say you're giving a presentation on those accused of offences during the recent English riots. It would be very easy to put together a series of figures cutting the data in various ways, as the Guardian have done here. Without commenting on the attributes of these particular figures, showing too many of them in a presentation risks diluting their power through loss of context.

There is an argument that sticking to plain figures serve a purpose in taking the political heat out of an issue, and refocusing on the evidence. There is some truth in that, but I would argue that researchers often go too far the other way and forget that after looking at umpteen tables and figures, it's all too easy to forget what we were talking about in the first place.

The riots are clearly a politically charged issue; images should be chosen with care. They might convey a message of community recovery such as the one above, or could emphasise lawlessness, as with this powerful but more conventional image from Greece in 2008 (mouseover both images for credits):

Garr Reynolds (Presentation Zen author and Thunderfly pin-up) puts it well:

Statistics...are just abstractions. But when we hear the story amplified by compelling photography...the issue becomes concrete.

As long as the image is a good fit with your evidence, then it provides a crucial hook for your audience, reminding them of what the data contained in your carefully crafted figure means in the 'real world'.

Next week, we'll look at how to quickly find high quality images that can be reproduced in your presentation or report. For now, I'd love to hear your views on using images in conjunction with the traditional academic figure. Do you think they help make an argument? Or does using images like those above risk overshadowing the research data?