Probability and Criticality

William F. Booth, CPPSecurity Assessment, Security Master Planning, Security Program Development


When evaluating what security concern to address first, where do you begin? Consider the probability and criticality of an event, and assign values based on standard criteria.


5 Almost certain. Barring major changes in circumstances, this event will occur or will occur frequently compared to other events. Or, historically, an event of this type has already occurred.
4 Very probable. This type of incident is more likely to occur than to not occur.
3 Probable. This type of event should occur if circumstances remain stable.
2 Improbable. This event is less likely to occur.
1 Unknown. More data is required to assign a rating.



5 Grave. A loss of this magnitude could result in the failure or long-term shutdown of the company or this event would definitely result in loss of life
4 Critical. A loss of this magnitude could have a major negative impact on company assets or could force a major change in the company’s investment strategy or this event may result in loss of life or definitely result in serious injury
3 Serious. A loss of this magnitude would have a noticeable impact on annual earnings or this event may result in serious injury.
2 Moderate. A loss of this magnitude would be covered by normal contingency funds.
1 Unknown. This is a temporary rating until more information is obtained, or the impact of the event is not known.

The total prioritized risk ranking is determined by first assigning the probability and criticality rankings and then multiplying these by each other. The resulting ranking should be ordered from high to low with the highest totals receiving the highest priority. For example, a “Grave” event with an “Almost certain” probability would receive a priority ranking of 25. This event would deserve the most attention.

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