A deviation is simply the difference between two sets of values. (Often referred to as a variance, which can cause confusion, as a variance is a statistical calculation between two values.) For our purposes (as described) I will refer to it as a deviation.
When you need to show how data:
- Moves away from another set of values.
Again, you are essentially displaying the difference between two values.
A few examples are:
- Budget versus actual financial performance.
- Current surgical wound infection rates compared to the previous year.
- HCAHPS scores compared to target.
The best graphs to display deviations or the difference between two sets of values are:
- Vertical Bar Graph
- Horizontal Bar Graph
If you also want to show a time series you can use a Line Graph.