Using the Mean and Standard Deviation

We now look in more detail at the calculations which are required to find the mean and the standard deviation.

As we have seen, the mean of a set of data values is the arithmetic average of those values, i.e. the total of the values divided by the number of values there are.

The standard deviation measures how much the data is spread about. It tells you how far away, on average, each member of the data set is from the mean.

The mean and standard deviation, used on their own just for one data set, give us a limited summary of what is going on. However, we often have several data sets which we want to compare, and there are various recognised procedures for making comparisons. The means and standard deviations of the data sets play a crucial part in the calculations.