Presentation by Jan Soderstrom of Catalyst Consulting on Probabilistic Risk Assessment to ASQ Section 1508 - Tampa/St Petersburg on March 9, 2009

1. Probabilistic Risk Assessment
Design Requirements
Test Programs
Field Information
Uncertainty, Legal & Regulatory

2. Safety
Safety:
♦Freedom from unacceptable risk of harm
♦ Probability of a hazardous event:
♦ Probable, occasional, remote, improbable, incredible
♦ Severity of the consequence of the hazardous event:
♦ Negligible, marginal, moderate, major, critical

3. Probability Labels
Qualitative labels signals a vague or uncertain probability
Interpretation of Qualitative labels depends on context
Users prefer quantitative data
Quantitative data may result in unwarranted assumptions
about precision of the data
Interpretation unduly influenced by absolute numbers

4. Types of Risk
♦ Voluntary Risk:
♦ Rock climbing, race car driving, horse
jumping, smoking, diving
♦ Involuntary Risk:
♦Natural disasters, sickness

5. Risk and Fear
Woody Allen’s definition of major surgery:
“Anything being done to me”
Greater fear of Human made risks than
natural risks
Voluntary risk less threatening than other
Highly personal

6. US Mortality Rate (per year)
Mortality Rate per 100,000 Population (1996)
3000
2500
2000
1500
1000
500
0
0 to 1 1 to 4 5 to 14 15-24 25-44 45-64 64-84
Age Group

7. Frequency Scales
Yearly mortality rate for 25-44 year olds in the US: 192 per 100,000
Risk of accidental death: ………………………… 33 per 100,000
1/10 th Risk of accidental death: …………………… 3.3 per 100,000
Average mortality rate: …......... 1000 per 100,000

8. Risk Tolerance
Mortality
Risk
Disease Mortality Rate
Overall
Accidents
Natural
Hazards
Perceived Benefit

9. Natural Hazards
Lightning death Rate: 0.041 per 100,000
Tornadoes: 0.027 per 100,000
Natural “Ave”………. 0.1 per 100,000
One Per Million

10. US Mortality Rates
Lung Cancer 56 per 100,000
Traffic Accident (Car): 22 per 100,000
10 Aircraft trips/yr: 0.1 per 100,000
(fatal and serious)
Commercial Diving: 200 per 100,000

11. Consumer/Producer Risk
Patients/Consumer
Acute
Chronic
Pediatrics, geriatrics…..
Donor
Manufacturer
• # of Devices
• # of Procedures

12. Devices
FD = 1/10,000 Procedures
Patient/Consumer
Acute 1/10,000
Chronic (/yr) 3.65/100
Pediatrics, geriatrics….. ??
Donor ??
Manufacturer
• # of Devices: 2500
• # of Procedures/Device/yr: 100
• P(FD) = 1/10,000*2500*100 = 25

13. Risk Tolerance
Mortality
Risk
1/100 Disease
1/1000
Accidents
1/10,000
1/100,000
Natural
1/1,000,000
Hazards
Perceived Benefit

14. Summary
Systems, not Components
Systematic failures hard to predict
Manufacturers burden to determine
acceptable risk levels, probability and
severity
Life Cycle
Use environment