A4.1 The following illustrates how confidence levels are used in different contexts in qualifying a risk rating. Public Safety Canada has issued the 'All Hazards Risk Assessment Methodology Guidelines 2012-13'. As part of the risk assessment process, risk assessors must also indicate their level of confidence:1

Confidence Level and Justification for Likelihood Analysis and Impact/Consequence Analysis

For each impact category, assessors must indicate their level of confidence in the estimates they have provided with respect to harm caused by the defined Risk Event Scenario. A confidence level from A to E is used to describe the confidence of assessors in the value they have defined or selected. The degree of confidence in the ratings produced will vary, depending on the availability of data, relevant experience and existing body of knowledge. Capturing the confidence level associated with each rating produced provides a crucial piece of information that helps complete the risk assessment picture. Confidence levels will be presented, along with final results, to indicate to decision makers where some low or very low confidence assessments may necessitate caution in interpretation. On the other hand, assessments accompanied with high or very high confidence levels will inspire trust in immediate actions required to treat pressing risks.

The following table presents definitions for confidence levels that must be used for each rating:

Confidence Level Quantification
A Very High confidence in the judgement based on a thorough knowledge of the issue, the very large quantity and quality of the relevant data and totally consistent relevant assessments.
B High confidence in the judgement based on a very large body of knowledge on the issue, the large quantity and quality of the relevant data and very consistent relevant assessments.
C Moderate confidence in the judgement based on a considerable body of knowledge on the issue, the considerable quantity and quality of relevant data and consistent relevant assessments.
D Low confidence in the judgement based on a relatively small body of knowledge on the issue, the relatively small quantity and quality of relevant data and somewhat consistent relevant assessments.
E Very Low confidence in the judgement based on small to insignificant body of knowledge on the issue, quantity and quality of relevant data and/or inconsistent relevant assessments

In addition, any justifications, assumptions and/or references for the various inputs defined by assessors during Risk Analysis should be recorded, along with the rating of each impact category.


1 Public Safety Canada has issued the 'All Hazards Risk Assessment Methodology Guidelines 2012-13', page 24.