Probabilistic Risk Assessment

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Presentation by Jan Soderstrom of Catalyst Consulating to ASQ 1508 section Tampa/St Petersburg on March 9, 2009

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Probabilistic Risk Assessment

  1. 1. Probabilistic Risk Assessment <ul><li>Design Requirements </li></ul><ul><li>Test Programs </li></ul><ul><li>Field Information </li></ul><ul><li>Uncertainty, Legal & Regulatory </li></ul>
  2. 2. Safety <ul><li>Safety: </li></ul><ul><ul><ul><li>Freedom from unacceptable risk of harm </li></ul></ul></ul><ul><li>Probability of a hazardous event : </li></ul><ul><ul><ul><li>Probable, occasional, remote, improbable, incredible </li></ul></ul></ul><ul><li>Severity of the consequence of the hazardous event: </li></ul><ul><ul><ul><li>Negligible, marginal, moderate, major, critical </li></ul></ul></ul>
  3. 3. Probability Labels <ul><li>Qualitative labels signals a vague or uncertain probability </li></ul><ul><li>Interpretation of Qualitative labels depends on context </li></ul><ul><li>Users prefer quantitative data </li></ul><ul><li>Quantitative data may result in unwarranted assumptions about precision of the data </li></ul><ul><li>Interpretation unduly influenced by absolute numbers </li></ul>
  4. 4. Types of Risk <ul><li>V oluntary Risk: </li></ul><ul><ul><ul><li>Rock climbing, race car driving, horse jumping, smoking, diving </li></ul></ul></ul><ul><li>I nvoluntary Risk: </li></ul><ul><ul><ul><li>Natural disasters, sickness </li></ul></ul></ul>
  5. 5. Risk and Fear <ul><li>Woody Allen’s definition of major surgery: </li></ul><ul><ul><li>“Anything being done to me” </li></ul></ul><ul><li>Greater fear of Human made risks than natural risks </li></ul><ul><li>Voluntary risk less threatening than other </li></ul><ul><li>Highly personal </li></ul>
  6. 6. US Mortality Rate (per year)
  7. 7. Frequency Scales <ul><li>Yearly mortality rate for 25-44 year olds in the US: 192 per 100,000 </li></ul><ul><li>Risk of accidental death: ………………………… 33 per 100,000 </li></ul><ul><li>1/10 th Risk of accidental death: …………………… 3.3 per 100,000 </li></ul><ul><li>Average mortality rate: …......... 1000 per 100,000 </li></ul>
  8. 8. Risk Tolerance Mortality Risk Natural Hazards Overall Accidents Perceived Benefit Disease Mortality Rate
  9. 9. Natural Hazards <ul><li>Lightning death Rate: 0.041 per 100,000 </li></ul><ul><li>Tornadoes: 0.027 per 100,000 </li></ul><ul><li>Natural “Ave”………. 0.1 per 100,000 </li></ul><ul><li>One Per Million </li></ul>
  10. 10. US Mortality Rates <ul><li>Lung Cancer 56 per 100,000 </li></ul><ul><li>Traffic Accident (Car): 22 per 100,000 </li></ul><ul><li>10 Aircraft trips/yr: 0.1 per 100,000 </li></ul><ul><li>Commercial Diving: 200 per 100,000 </li></ul>(fatal and serious)
  11. 11. Consumer/Producer Risk <ul><li>Patients/Consumer </li></ul><ul><ul><li>Acute </li></ul></ul><ul><ul><li>Chronic </li></ul></ul><ul><ul><li>Pediatrics, geriatrics….. </li></ul></ul><ul><ul><li>Donor </li></ul></ul><ul><li>Manufacturer </li></ul><ul><ul><ul><li># of Devices </li></ul></ul></ul><ul><ul><ul><li># of Procedures </li></ul></ul></ul>
  12. 12. Devices F D = 1/10,000 Procedures <ul><li>Patient/Consumer </li></ul><ul><ul><li>Acute 1/10,000 </li></ul></ul><ul><ul><li>Chronic (/yr) 3.65/100 </li></ul></ul><ul><ul><li>Pediatrics, geriatrics….. ?? </li></ul></ul><ul><ul><li>Donor ?? </li></ul></ul><ul><li>Manufacturer </li></ul><ul><ul><ul><li># of Devices: 2500 </li></ul></ul></ul><ul><ul><ul><li># of Procedures/Device/yr: 100 </li></ul></ul></ul><ul><ul><ul><li>P(F D ) = 1/10,000*2500*100 = 25 </li></ul></ul></ul>
  13. 13. Risk Tolerance Mortality Risk 1/100 1/1000 1/10,000 1/100,000 1/1,000,000 Natural Hazards Accidents Perceived Benefit Disease
  14. 14. Summary <ul><li>Systems, not Components </li></ul><ul><li>Systematic failures hard to predict </li></ul><ul><li>Manufacturers burden to determine acceptable risk levels, probability and severity </li></ul><ul><li>Life Cycle </li></ul><ul><li>Use environment </li></ul>

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