If you have reported an average value, it is a good idea to report how spread the dataset is too. This provides not only you the research but also the reader with better insight into how variable (or spread out) the dataset is.

**Which measure of spread should I report?**

The measure of spread to use will depend on which average value you have chosen to report for your dataset. As a general guide if you have reported:

- The
**mode** then you could report the **range** of the data.
- The
**median** then you should report the **interquartile range** of the data.
- The
**mean** then you should report the **standard deviation** of the data.

Details of these measures of spread are provided below.

**Range: **The range of a data set is the difference between the largest (maximum) and smallest (minimum) values in the data set. Take a look at the following example of the range by Maths is Fun.

Calculate: Range = Maximum - Minimum

Calculate using Excel: Range = MAX(dataset) - MIN(dataset)

**Interquartile Range (IQR):** The interquartile range captures the middle 50% of ordered data. Take a look at the following example of interquartile range by Maths is Fun.

Calculate:

- Order data from smallest to largest.
- Find the values that are at the first (Q1) and third (Q3) quartile.
- The interquartile range is the difference between the third and first quartile:
IQR = Q3 - Q1

Calculate using Excel: IQR = Q3 - Q1

where Q1 and Q3 are found using the quartiles function

Q1 = QUARTILE.EXC(datarange,**1**)

Q3 = QUARTILE.EXC(datarange,**3**)

### Population and Samples

Want to know more about populations and samples. Take a look at the following page ‘ Population vs sample: what’s the difference?’ by Pritha Bhandari.

#### Additional resources:

- A short guide from the statstutor with examples of how to perform the calculations by hand and SPSS.
- Practical examples and illustrations of measures of spread by Laerd statistics.