To equate or not to equate


One of our jobs, working in academia, is giving talks. I don’t mean teaching, but rather presenting research. Lately I have had a spate of talks to give, largely as a result of being new in my Department.

My research involves maths, or rather the underlying principles of what I do involves quite alot of maths. When I give a talk sometimes I use equations and sometimes I don’t. It depends what I am talking about and who I am talking to. I have been thinking lately about when and when not to use maths in a presentation. I have also been polling people – my friends and my colleagues – to ask them what they think about equations in presentations.

About a third of the people I asked said – you should never have equations in a talk. Absolutely never, full stop. The challenge is to explain what you do without ever ‘resorting’ to an equation.

I think it is very good and indeed a challenge to be able to explain your research entirely in words. However, I am not sure I agree that a ‘just say no’ to equations mentality is the right way to go. While you don’t have to make equations the focal point of everything, why should you not talk about maths if mathematics is integral to what you do?

I think there is an assumption that most people will be put off by maths? Perhaps most people are but is this the right response? To just ignore equations completely? There may well be some people that might WANT to see the maths, I know sometimes I do.

While it is true that sometimes equations seem to be used in lieu of saying ‘I can’t really explain what I am talking about so I will put in a big equation‘, I think the real trick is to learn how to explain research both mathematically and in words. Especially if maths is a large part of your research. If you learn how to do both you can adjust any lecture accordingly.

I don’t think we should be afraid of maths. Systematically leaving equations out of talks isn’t necessarily the best thing to do, especially if you can talk someone through the equation. For instance, one of the underlying equations I use is just a sum, it is rare you find someone who just can’t add. So what is so bad about saying “This equation is a sum. Fundamentally what you measure in this experiment is just a sum of things and here is how you understand this equation…..”

About Sylvia McLain

Girl, Interrupting aka Dr. Sylvia McLain used to be an academic, but now is trying to figure out what's next. She is also a proto-science writer, armchair philosopher, amateur plumber and wanna-be film-critic. You can follow her on Twitter @DrSylviaMcLain and Instagram @sylviaellenmclain
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3 Responses to To equate or not to equate

  1. Guillaume Collet says:


    I asked myself about this when I was preparing my phd defense talk… and I agree with you. When math are the fondations of your work, you cannot avoid equations. But you need to find a way to explain what it means.

    When I have a big equation to present, my challenge is to explain the meaning of each part, what is the big idea and why we need it. People do not have to understand everything, but they need to know what’s “behind”.

    Giving a big equation without explanations is like saying : “I don’t know how it works but it’s pretty, isn’t it ?”… not really impressive…

  2. Martyn Rittman says:

    Having a background in maths I like to see equations, but as you say it’s all about the audience. Also, define and explain your terms! I think that’s what can make the difference between an ‘I don’t really understand what I’m doing’ equation and one that actually enhances your talk.

  3. cromercrox says:

    There’s nothing so elegant as a well-turned equation. So, have equations – but explain every term at a snail’s pace; explain what it all means when it’s put together… and then repeat the conclusions for those mathematically challenged people (such as me) who won’t have gotten it the first time.

    The picture at the head of the post reminds me of a cartoon I saw years ago. A mathematician had filled an entire blackboard with equations. A more senior colleague came up and said words to the effect of ‘there’s more to maths than filling a blackboard.’

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