1. Qualitative Risk Assessment Charles Yoe, PhD cyoe1@verizon.net Institute for Water Resources 2009

2. The Need Manage risk intentionally Do better than has been done Quantitative risk assessment not always possible or necessary Qualitative risk assessment can be a viable option –Partial assessments are often useful

3. Use Qualitative Assessment When consistency and transparency in handling risk are desired When theory, data, time or expertise are limited When dealing with broadly defined problems where quantitative risk assessment is impractical

4. Qualitative Risk Assessment The process of compiling, combining and presenting evidence to support a statement about risk –Descriptive or categorical treatment of information Is formal, organized, reproducible method based on science and sound evidence Flexible and consistent Easy to explain to others Supports risk management decision making

5. Qualitative Methods Toolbox Increase or Decrease Risk Risk Narratives Evidence Mapping Screening Ratings Rankings Enhanced Criteria Ranking Operational Risk Management (Risk Matrix) Develop a Generic Process Qualitative Assessment Models Multi-Criteria Decision Analysis

6. Qualitative Assessment May include all or just some of the risk assessment steps Qualitative risk characterization is usually the endpoint Not every qualitative assessment is a true risk assessment

7. For Any Method Necessary preparation! –Identify the problem –Identify the goals –Identify the questions to be answered Use an assessment framework

8. Increase or Decrease Risk For some problems it may be enough to know if things are getting better or worse Identify the direction of change in a risk and the specific reasons for it Storm damage has weakened structure Funding uncertainty clouds future Clarifies thinking and rationale Not good for netting changes

9. Risk Narratives What can go wrong? How can it happen? How likely is it? What are the consequences? Use simple narratives that answer these questions honestly Tell story of existing risk Tell story of mitigation effectiveness (risk reduction) Tell story of residual, transferred or transformed risk

10. Evidence Frameworks A risk evaluation technique Identify how experts evaluate current scientific evidence on chosen topics What conclusions do they reach regarding risk potential What evidence/arguments do they use to justify conclusions What consensus/disagreement exists What uncertainties remain Source: Risk evaluation of the health effects of mobile phone communication (10/2005) by Peter Wiedermann, Holger Schütz, and Albena Spangenberg

11. Core Elements Evidence base or data Pro and con arguments, the warrants –Includes respective supporting or attenuating arguments Conclusions of claim about existence of a hazard with remaining uncertainties

13. Ordering Techniques Screening, rating and ranking with increasing levels of detail/information Used to identify hazards, commodities, commodity-pathogen pairs, pathways, mitigation measures, potential risk and the like that are of interest to decision makers

14. Screening Process of separating elements into categories of interest and no interest through systematic elimination Requires Items to be screened Carefully defined categories (yes/no) Criteria for screening Evidence for the criteria An algorithm for using the criteria to separate the items into the desired categories

15. Screening Algorithms Domination procedures (better/worse on all criteria) Conjunctive procedures (meets all criteria thresholds) Disjunctive procedures (meets a least one criterion threshold) Elimination by aspects (set cut-off value for most important criterion and eliminate, then set cut-off value for next most important criterion, etc.) Lexicographic rules (rank against all criteria then rank alternatives)

16. Rating Systematic process of separating elements into multiple categories of varying degrees of interest Individuals are rated High, medium, low, no risk Requires Items to be rated Carefully defined categories (non-ordinal is okay) Criteria for rating Evidence for the categories An algorithm for using the criteria to separate the items into the desired categories

17. Ranking Systematic process used to put items in an ordinal sequence Rated items can be ranked May rely on ordinal ranked categories or an ordinal ranking of each individual item Simple when objective measures of a risk or other characteristic of interest are available Requires Items to be ranked (alternatives) Carefully defined science-based criteria for ranking Evidence of each item’s measurement or rating for each criterion Differential weights for criteria when appropriate A synthesis algorithm.

18. Enhanced Criteria Based Ranking Criteria Ratings All Possible Combinations of Ratings Ranking Evaluate Reasonableness of Ranking Add Criteria New Combinations of Ratings New Ranking

19. Question? Which lock gates in division present the greatest potential risk to health and safety and therefore should be repaired first?

20. Step One: Criteria Assume criteria equally important (or not). Reflect most important aspects of evaluating risk. Define H, M, L scenarios for each criterion. Use three or four evidence-based criteria.

21. Step Two: Rating Use expert judgment to critically evaluate the available information Develop estimates for each “hazard” against criteria Use letters or numbers but numbers do not represent an absolute measurement of risk only a relative means for comparison

22. Step Three: All Possible Combinations Greatest RiskHHH HHM, HMH, MHH HHL, HLH, LHH, HMM, MMH, MHM HLM, MHL, HML, LMH, MLH, MMM, LHM HLL, LHL, LLH, MML, LMM, MLM MLL, LML, LLM Least RiskLLL This is for equally weighted criteria. Unequal weights yield different listings.

23. Step Four: Rank Subjectively Establish rank according to descending relative risk Identify subjective clusters.

24. Step Five: Add Criteria? Look at rankings, do they make sense? Have you thought properly about this issue? If they do not, perhaps you did not consider all the most relevant criteria A new criteria may be added to more accurately reflect the assessors rationale for ranking

25. Step Five: Add Criteria? (cont) Suppose the following was added to our example Criterion 4: Cost of emergency repair –H = Major disruptions to navigation or power, much higher costs to repair –M = Much higher costs to repair –L = Same as scheduled repair

26. Step Six: New Ratings

27. Step Seven: New Ranking

28. Operational Risk Management (ORM)

29. Steps Determine purpose and use of matrix –Identify the question to be answered Define consequences of interest Identify consequence ranges and definitions Identify likelihood ranges and definitions Identify levels of risk in the cells of the matrix

30. Your DE Has Seen This “Mishap Risk” DOD "Standard Practice For System Safety” MIL-STD-882D 10 February 2000

31. Consequence Severities

32. Probability Levels

33. Risk Assessment Values Each risk you assess is placed in a cell and managed accordingly

34. Risk Levels

35. Another Example Source: Assessing Environmental Risk, A Lecture to the Irish Environmental Law Association By: L. M. Ó Cléirigh 29 June 2004

36. Risk Matrix

37. Three Axioms Weak consistency Betweenness Consistent coloring 3x3 and 4x4 should look like this to minimize problems Source: What’s wrong with risk Matrices? By Louis Anthony Cox, Risk Analysis Vol. 28 No.2, 2008

38. The Risk Management Point of Matrix

39. Probability of Adverse Impact Consequence of Adverse Impact Age x Condition x Usage x Event Risk = Generic Process Economic Environmental Perceived Damage Damage Damage Potential + + X

40. Qualitative Assessment Models Probability hazard exists- rank as H,M,L Probability adverse consequence occurs if exposed-rank as H,M,L Probability exposure occurs-rank as H,M,L Overall risk estimate, integrate hazard, consequence, exposure- rank as H,M,L

41. MCDM/MCDA Multi-Criteria Decision Making (MCDM) is the study of methods and procedures by which concerns about multiple conflicting criteria can be formally incorporated into the management planning process Decision maker contemplates choice of action in an uncertain environment MCDA helps people choose among a set of pre-specified alternatives Decision making relies on information about these alternatives Quality of information can be scientifically-derived hard data to subjective interpretations Outcomes of decisions may be certain (deterministic information) or uncertain represented by probabilities and fuzzy numbers MCDA can assist in information processing and may lead to better decisions

47. Take Away Points Not all risk assessment needs to be quantitative Develop a few consistent and well developed techniques for your usage

48. Charles Yoe, Ph.D. cyoe1@verizon.net Questions?