This video takes a look at the ways we can measure the spread of data about the median. It first looks at the range. It looks at how to calculate it and why it's not very useful when there are outliers. It moves on to look at the Interquartile Range. It shows how to find the IQR and what each of the parts mean. It also looks at how the IQR removes the problems created by the outlier. This video is part of the Year 9 series on Mathematics.