7.8 Do Not Use Common Practice Matrix Approaches, PIGs, FMEAs
101
This adds to risk-matrix-generated confusion. Ascending or, even worse, descending
indexes increase the distance between a matrix-based risk assessment and reality.
Rankings are arbitrary and misleading.
Instability Because of Categorization
Categories are the cardinal (index) given to probabilities and consequences
ranges. Categories generate “instability” as they influence the “binning exercise” necessary to compile a risk matrix. Arbitrary range limits and categories are not necessary, as we have shown in Ten Rules for Preparing Sensible Risk Assessments (http://www.riskope.com/wp-content/uploads/2016/11/TenRules-For-Sensible-Risk-Assessments.pdf).
Relative Distance is Distorted
The fact that risk-matrix axes display, explicitly or not, values in logarithmic scale
distorts the distance between points. This is a phenomenon that occurs in many
instances in science and economy. Unless properly explained and conveyed to
users, this distance distortion leads to significant misunderstandings. Beyond the
publications cited above we discussed this theme in detail in a 2013 blogpost
have-a-heated-discussion-about-fmeapigs-common-practices-and-what-a-rationaland-transparent-quantitative-risk-assessment-should-encompass/).
7.8.3 Can We Solve the Problem of Risk Matrices
Deficiencies?
We show two ways:
Correcting a Series of Common Mistakes
A 2016 paper (Oboni et al. 2016) explores the idea that correcting a series of common
mistakes, which can be done quite easily and inexpensively, would lead to an honest
and more representative way to assess risks.
Housekeeping of Risk Register
In many instances clients call us for help with meaningless third-party risk matrices.
We define the cause of that call as the “two hundred yellow syndrome”. Indeed, the
risk matrix’s numerous deficiencies lead to many risks being binned in the central,
generally “yellow”, area of the matrix.
Furthermore, confusion in the hazards, consequences and risk scenario descriptions leads to added confusion. The “housekeeping of the risk register” consist in
eliminating confusion by first strictly abiding to a well-defined glossary (https://www.
riskope.com/knowledge-centre/tool-box/glossary/). Once the register is consistent,
we vet the risks one by one, look at possible common cause failures, interdependencies and rationalize probabilities and consequences. The final result is a p-C graph
unencumbered by arbitrary cell limits.
101
This adds to risk-matrix-generated confusion. Ascending or, even worse, descending
indexes increase the distance between a matrix-based risk assessment and reality.
Rankings are arbitrary and misleading.
Instability Because of Categorization
Categories are the cardinal (index) given to probabilities and consequences
ranges. Categories generate “instability” as they influence the “binning exercise” necessary to compile a risk matrix. Arbitrary range limits and categories are not necessary, as we have shown in Ten Rules for Preparing Sensible Risk Assessments (http://www.riskope.com/wp-content/uploads/2016/11/TenRules-For-Sensible-Risk-Assessments.pdf).
Relative Distance is Distorted
The fact that risk-matrix axes display, explicitly or not, values in logarithmic scale
distorts the distance between points. This is a phenomenon that occurs in many
instances in science and economy. Unless properly explained and conveyed to
users, this distance distortion leads to significant misunderstandings. Beyond the
publications cited above we discussed this theme in detail in a 2013 blogpost
have-a-heated-discussion-about-fmeapigs-common-practices-and-what-a-rationaland-transparent-quantitative-risk-assessment-should-encompass/).
7.8.3 Can We Solve the Problem of Risk Matrices
Deficiencies?
We show two ways:
Correcting a Series of Common Mistakes
A 2016 paper (Oboni et al. 2016) explores the idea that correcting a series of common
mistakes, which can be done quite easily and inexpensively, would lead to an honest
and more representative way to assess risks.
Housekeeping of Risk Register
In many instances clients call us for help with meaningless third-party risk matrices.
We define the cause of that call as the “two hundred yellow syndrome”. Indeed, the
risk matrix’s numerous deficiencies lead to many risks being binned in the central,
generally “yellow”, area of the matrix.
Furthermore, confusion in the hazards, consequences and risk scenario descriptions leads to added confusion. The “housekeeping of the risk register” consist in
eliminating confusion by first strictly abiding to a well-defined glossary (https://www.
riskope.com/knowledge-centre/tool-box/glossary/). Once the register is consistent,
we vet the risks one by one, look at possible common cause failures, interdependencies and rationalize probabilities and consequences. The final result is a p-C graph
unencumbered by arbitrary cell limits.