Risk Acceptability
Safe does not necessarily mean „free from risk‟
Session 21 1
Most Risks have Associated Benefits
Session 21
2
“Acceptable risk is the risk associated with the best of available alternatives, not with the best of alternatives which we would hope to have available.”
Source: Derby, Stephen L., and Ralph L. Keeney, 1981.
Session 21
3
Factors that Determine Risk Acceptability
• Personal • Political / Social • Economic
Session 21
4
Injustices
• The process of determining the acceptability of risk can be influenced by those with money and vested interests. • Setting a dollar figure (in cost-benefit analyses) on a human life is considered by many to be unethical and unconscionable. • Risk management is usually an undemocratic process, as those who may be harmed are not identified or asked if the danger is acceptable to them.
Session 21 5
Risk Acceptability Assessment Methods
• • • • • • • “No Go” Alternative Accept the Risk Establish a “De Minimis Risk” Level Establish a “De Manifestis Risk” Level Perform a Cost-Benefit Analysis Perform Cost Effectiveness Choose the Best Choice Among Alternatives
Session 21 6
Derby and Keeney‟s 5 Steps
• Define the alternatives • Specify the objectives and measures of effectiveness to indicate the degree to which they are achieved • Identify the possible consequences of each alternative • Quantify the values for the various consequences • Analyze the alternatives to select the best choice
Source: Derby and Keeney, 1981
Session 21
7
COST
Example A
•K •L *M
0
0
RISK
Source: Derby, Stephen L., Ralph L. Keeney. 1981. Risk Analysis: Understanding “How Safe Is Safe Enough?” Risk Analysis. V.1. No.3. Pp.217-224.
Session 21
8
COST
Example B
Minimum Risk
•K •L
0
Minimum Cost
0
RISK
Source: Derby, Stephen L., Ralph L. Keeney. 1981. Risk Analysis: Understanding “How Safe Is Safe Enough?” Risk Analysis. V.1. No.3. Pp.217-224.
Session 21
9
COST
Example C
•K
*M •L
*
0
0
RISK
Source: Derby, Stephen L., Ralph L. Keeney. 1981. Risk Analysis: Understanding “How Safe Is Safe Enough?” Risk Analysis. V.1. No.3. Pp.217-224.
Session 21
10
COST
Example D
Case 1
•K •L Case 2
0
0
RISK
Source: Derby, Stephen L., Ralph L. Keeney. 1981. Risk Analysis: Understanding “How Safe Is Safe Enough?” Risk Analysis. V.1. No.3. Pp.217-224.
Session 21
11