The Risk Matrix
The risk matrix is a graphical construction used to display risk severity. The illustration below shows a typical risk matrix. You can control all aspects of your matrix design.
The risk matrix defines the number of levels your impact and probability scales will have. A 3x3 risk matrix will result in 3-level impact and probability scales, a 5x5 matrix, as shown below, will result in 5-level scales, and so on.
Risk matrix size is set via the Datafile Setup form. This is usually done when the datafile is created, but can be done later via menu call Setup Menu/Datafile Setup. All other matrix characteristics are set via the Risk Matrix designer, accessible via menu command Setup Menu/Risk Matrix. These characteristics include:
• Number of zones
• Zone boundaries
• Zone colors
• Risk rank values
• Axis labels
• Probability scale type (equal intervals or decade intervals)
Your risk matrix may be of any size from 2x2 to 10x10. The matrix size determines the number of levels in your impact and probability scales. A 2x2 matrix will result in 2-level scales, a 3x3 matrix in 3-level scales, and so on.
The matrix size may not be changed once you have defined any impact assessment scales. If you wish to change the matrix size after any impact scales have been set up, the only way it can be done is by deleting all your scales, changing the matrix size, and then re-entering the scales. You will also have to revisit any existing risk assessments.
You can generate risk matrix reports showing the data in terms of a reduced matrix (data compression option), but you cannot generate reports in terms of an expanded matrix. It is therefore recommended that you set the matrix size when the datafile is first opened to be the largest size that you will ever need to use. The default matrix size is 5x5.
Number of Zones
The matrix can be separated into a number of colored zones, giving a relatively crude measure of risk severity. For example, a 3-zone matrix, as shown above, can be used to divide risks into groupings of major, moderate and minor risks (red zone represents major risks, yellow zone moderate, and green zone minor risks).
You may have from 1 to 6 zones on your matrix, except for a 2x2 matrix which is physically limited to a maximum of 4 zones.
The zone boundaries define the relative size and shape of each zone, and hence how risks are grouped into different severity levels. Zone boundaries are under your control. You may alter them using an automatic process built into the Risk Matrix Definition form, or you may change them manually.
You may select the color applied to each zone from a palette of 16 colors.
Risk Rank Values
If a large number of risks have been identified it can often be difficult to decide which should be given priority. In such cases the risk rank system can be used to introduce a finer risk classification system than the matrix zones.
The vertical axis always shows probability and the horizontal axis impact. The risk matrix axes are labelled Probability and Impact by default. However, you may give them whatever labels you wish. The vertical axis label is limited to a maximum of 14 characters.
Probability Scale Type
The matrix probability scale can be an equal intervals scale or an equal multiples decade scale. You may change the scale type at any time. The positions of individual risks on the matrix will generally change if the scale type is changed.