**Showing Uncertainty of a Calculated
Mean/ Average for a Data Set **

You can use standard deviation as a way to show how accurate a mean of a data set is.

1. You first calculate the standard deviation for the data set, which in the example below is +/- 2.2.

2. You then record the mean for the data set (125 bpm in the example below) and place the standard deviation value you calculated after it. The result is 125 bpm +/- 2.2.

This means the average exercise heart rate may on average vary between 122.8 bpm to 127.2 bpm.

**[How to Use Standard
Deviation to Compare Data Sets]**