EN 31010 Guida alle Tecniche di Valutazione del Rischio: elenco / scelta

ID 4040 | Rev. 1.0 del 04.07.2019

Il Documento, estratto dal draft 2018 della norma e dall'allegato informativo A (pubblicata come UNI CEI EN IEC 31010:2019), illustra le "Tecniche di Valutazione del Rischio", dalle definizioni delle fasi del processo di VR, alle tecniche/metodi e la scelta opportuna in relazione:

- alle fasi del processo (Tabella 1)
- ai fattori del processo (Tabella 2).

Questa Norma internazionale serve all'applicazione della Norma ISO 31000 e fornisce una guida per la  scelta e l'applicazione di tecniche sistematiche per la valutazione del rischio.

La valutazione del rischio effettuata in conformità a questa Norma rientra nell'ambito più ampio della gestione dei rischi.

In questa Norma si presenta l'applicazione di diverse tecniche, con specifico riferimento ad altre norme internazionali dove il concetto e l'applicazione delle singole tecniche sono descritte in maggior dettaglio.

La seconda edizione del 2019 annulla e sostituisce la prima edizione pubblicata nel 2009.

Data di pubblicazione: 13.06.2019

Comitato Tecnico: CT 56

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Introduction

This document provides guidance on the selection and application of various techniques that can be used to help improve the way uncertainty is taken into account and to help understand risk.

The techniques are used:

- where further understanding is required about what risk exists or about a particular risk;
- within a decision where a range of options each involving risk need to be compared or optimized;
- within a risk management process leading to actions to treat risk.

The techniques are used within the risk assessment steps of identifying, analysing and evaluating risk as described in ISO 31000, and more generally whenever there is a need to understand uncertainty and its effects.

The techniques described in this document can be used in a wide range of settings, however the majority originated in the technical domain. Some techniques are similar in concept but have different names and methodologies that reflect the history of their development in different sectors. Techniques have evolved over time and continue to evolve, and many can be used in a broad range of situations outside their original application. Techniques can be adapted, combined and applied in new ways or extended to satisfy current and future needs.

This document is an introduction to selected techniques and compares their possible applications, benefits and limitations. It also provides references to sources of more detailed information.

The potential audience for this document is:

- anyone involved in assessing or managing risk;
- people who are involved in developing guidance that sets out how risk is to be assessed in
- specific contexts;
- people who need to make decisions where there is uncertainty including:

      - those who commission or evaluate risk assessments,
      - those who need to understand the outcomes of assessments, and
      - those who have to choose assessment techniques to meet particular needs.

Organizations that are required to conduct risk assessments for compliance or conformance purposes would benefit from using appropriate formal and standardized risk assessment techniques.

Core concepts

Uncertainty

Uncertainty is a term which embraces many underlying concepts. Many attempts have been made, and continue to be developed, to categorize types of uncertainty.

One distinction that is sometimes useful is between:

- uncertainty which recognises the intrinsic variability of some phenomena, and that cannot be reduced by further research; for example, throwing dice (sometimes referred to as aleatory uncertainty) and
- uncertainty which generally results from a lack of 294 knowledge and that therefore can be reduced by gathering more data, by refining models, improving sampling techniques etc. (sometimes referred to as epistemic uncertainty).

In many situations both types of uncertainty are faced.

Other commonly recognized forms of uncertainty include:

- linguistic uncertainty, which recognizes the vagueness and ambiguity inherent in spoken languages;
- decision uncertainty, which has particular relevance to risk management strategies, and which identifies uncertainty associated with value systems, professional judgement, company values and societal norms.

Thus uncertainty, in its broader sense, can encompass:

- uncertainty as to the truth of assumptions, including presumptions about how people or systems might behave;
- variability in the parameters on which a decision is to be based;
- uncertainty in the validity or accuracy of models which have been established to make predictions about the future;
- events (including changes in circumstances) whose occurrence or character are uncertain;
- uncertainty associated with disruptive events;
- the uncertain outcomes of systemic issues, such as shortages of competent staff, that can have wide ranging impacts which cannot be clearly defined;
- lack of knowledge about something;
- lack of knowledge which arises when uncertainty is recognized but not fully understood;
- unpredictability;
- the inability of the human mind to discern complex data, situations with long-term consequences, and bias-free judgments.

Not all uncertainty can be understood, and the significance of uncertainty might be hard or impossible to define or influence. However, a recognition that uncertainty exists in a specific on text enables early warning systems to be put in place to detect change and arrangements to be made to build resilience to cope with unexpected circumstances.

Characteristics of risk

In general terms risk includes the effects of any of the forms of uncertainty described in clause 4.1.

One way of describing risk is as a set of consequences and their likelihoods that might occur as a result of defined but uncertain events. These might have multiple causes and lead to multiple effects. Not all risks can be described in these terms. There is not always an identifiable event. Further, sources of risk also can include inherent variability, human behaviour and organizational structures and arrangements. In addition consequences may take a number of discrete values, be continuous variables or be unknown. They may be positive, negative or both. Consequences may not be discernible or measurable at first, but may accumulate over time. It follows that risk cannot always be tabulated easily as a set of events, their consequences and their likelihoods.

Risk assessment techniques aim to help people understand uncertainty and the associated risk in this broader, more complex and more diverse context, for the primary purpose of supporting better-informed decisions and actions.

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Table A.1 – Characteristics of techniques

A.2 Application of categorization of techniques

Table A.2 lists a range of techniques classified according to these characteristics. The techniques described represent structured ways of looking at the problem in hand that have been found useful in particular contexts. The list is not intended to be comprehensive but covers a range of commonly used techniques from a variety of sectors. For simplicity the techniques are listed in alphabetical order without any priority.

Each technique is described in more detail in Annex B. The techniques in Annex B are grouped according to how they are most commonly used in risk assessment. Within each grouping techniques are arranged alphabetically and no order of importance is implied.

Note The majority of techniques in table A2and Annex B assume that risks or sources of risk can be identified.

There are also techniques which can be used to indirectly assess residual risk by considering controls and requirements that are in place (see for example IEC 61508).

Figure A.1 – Application of techniques in the risk management process

Table A.2 – Techniques and indicative characteristics

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IEC 31010:2018 Draft 
IEC 31010:2009

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