Psychology would seem, at first look, to be one of the sciences with the least involvement with mathematics. After all, psychology is all about the mind, all about people – what does mathematics have to do with that?

Well, as it turns out, a lot! The main reason is that mathematics is of use, is that psychology has one aspect that most people don’t consider. Most think of psychology as relating to a single person, but there is one other consideration. We also care about how groups respond, andĀ **how the individual compares to the group.**

To this end, we need a simple way to describe groups, so we can compare them to each other and to the individual. The best way to do thisĀ reliably is to use mathematics – and we are interested in two particular concepts – the idea of what the average value of a group is, and the idea of how much the group is distributed.

In this post, I will cover the basic mathematics you will need to describe these concepts – which you will need for your Empirical Research Activity (ERA) report that is due at the end of term 4. The mathematics is *not* difficult, and you will be able to the majority of it on your computer, by using microsoft excel (or a similar piece of software).

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