The severity and likelihood matrix is one method of expressing risk or determinng priority. A frequent problem that is serious needs to be addressed before a rare problem that is minor.



(1) x axis = severity

(2) y axis = likelihood or probability


The number of values along each axis may range from 4 or more. A Likert scale could be used.


The severity or likelihood of an outcome may not be linear, meaning that the value assigned to each axis may vary.


total number of cells in the matrix -

= (number of cells on the x-axis) * (number of cells on the y-axis)


risk value in each cell =

= (severity number along the x-axis) * (likelihood number along the y-axis)


If a 5 by 5 matrix is used, then risk values may range from 1 to 25.


Risk Value for a Cell

Priority or Risk

1 or 2


3 or 4

low to moderate

5 to 10


12 to 16

moderate to high

20 to 25



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