Qualitative/quantitative methods, risk

Although the main emphasis of this chapter will be on qualitative human reliability methods in risk assessment, this section will illustrate the importance of both qualitative and quantitative methods in CPQRA. An example of a typical assessment, described by Ozog (1985) will be considered. The stages of the risk assessment are as follows ... 

Consequence assessment for the purposes of establishing design basis differs from consequence assessment in the context of a risk analysis study (see Qualitative and Quantitative Methods, below). A qualitative, or semi-quantitative (order of magnitude) consequence severity estimate may suffice for the latter. 

Process Hazard Analysis— An organized effort to identify and evaluate hazards associated with chemical processes and operations to enable their control. This review normally involves the use of qualitative techniques to identify and assess the significance of hazards. Conclusions and appropriate recommendations are developed. Occasionally, quantitative methods are used to help prioritize risk reduction measures. 

Both qualitative and quantitative methods of analysis can be applied to the assessment of risk. 

In conclusion, the BRA is an important and complex task, relevant across the life cycle of a medicinal product. Structured and systematic BR approaches can improve clarity and ensure consistency. While the final BR conclusion mainly relies on qualitative judgment, quantification and integration of the benefits and risks can provide useful support for the BR decision. Several quantitative methods have been discussed in this chapter, and which method to use depends upon the specific situation at hand. Further development and understanding in quantitative BRA are needed to address the challenges mentioned previously. 

Based on any unacceptable and unmitigated risk identified during hazard analysis, further risk assessment and risk mitigation techniques need to be applied. LORA and conceptual SIS designs based on Risk Matrix can be employed if a qualitative to semi-quantitative method is preferred. Fault tree and event tree analyses with a robust LOPA can be applied if a quantitative method is essential... 

AS/NZS 4360 discusses different types of analysis, ranging from purely qualitative to purely quantitative ones. According to the Standard, the selection of the type of analysis should, amongst other, depend on the availability of numerical data and the proportionality of the time and effort needed for a fuller assessment. Unlike the AS/NZA 4360, Basel II is explicit about its preference for quantitative methods (for computing VaR). This difference can be attributed to the characteristics of the (financial) risks covered by Basel II while Basel II only deals with the financial sector, the AS/NZA 4360 Standard is supposed to fit a wide range of firms and industries. 

Qualitative and quantitative methods used in the industries for evaluating the potential risk and the safety performances as well as Ae methods for inspection ranking are discussed in the following ... 

HSE assessments have a long tradition within the oil-and gas industry. These assessments use a wide range of methodologies, from the strict quantitative methods such as QRA (Quantitative Risk Analysis) and FMECA (Failure Mode Effect and Criticality Analysis) to the more qualitative methods such as HAZOP (HAZard OPerability analysis). Most methods combine qualitative and quantitative data and approaches. For example, an FMECA basically uses generic failure data, expert judgments are likewise important. 

There are minor differences between the two decision processes. The SSCl is determined in a more qualitative way by using two factors, i.e. hazard severity and software autonomy. The SIL should he determined in a quantitative probabilistic way by computing the risks of the system and comparing with accepted risk levels. Thus the necessary risk reduction is determined which in tun determines the rehahhity requirement for the safety function. Risk graphs (see section 2.2) and risk maps are rather considered as qualitative estimation methods by lEC 61508. Finally we mention that the AOP 52 presents in chapter 11 in total 6 case studies where 3 are taken fi om the ammunition domain. Such specific examples are not available in the lEC 61508. 

An organized formal review to identify and evaluate and hazards with industrial facilities and operations to enable their safe management. The review normally employs a qualitative technique to identify and access the importance of hazards as a result of identified consequences and risks. Conclusions and recommendations are provided for risks that are deemed at a level not acceptable to the organization. Quantitative methods may be also employed to embellish the understanding of the consequences and risks that have been identified. 

A mixture of qualitative and quantitative methods was used in this work. These include reliability analysis, eapital investment costs, safety, feasibility and environmental impaet assessment (ElA). Tools used include failure mode and effect analysis (FMEA), environmental impaet assessment, and risk analysis. FMEA was used to conduct a reliability analysis, EIA was used to calculate the concentration of the flared gas eomposition partieles affeeting the local environment, and risk assessment was employed to find out the hazards and exposure in the case study in order to assure safety. Cost estimation was used to ealculate the capital investment cost for each option considered. Information and expert opinions were eaptured through interviews and questionnaires. 

Nevertheless, the influence that engineers have had in developing risk assessment methods is obvious. Their passion for numerical precision encourages the use of quantitative methods. As an example, in at least two industries quantitative Failure Modes and Effects Analyses (FMEAs), rather than qualitative FMEAs, are now required to meet quality assurance requirements. Mostly, engineers make those FMEAs. 

Cahbrated risk graph, described in the standard as a semi-qualitative method, but by some practitioners as a semi-quantitative method. 

The first definition begs the question What does several mean In practice it is likely to be very difficult to assess SIL requirements unless there is a set of agreed definitions of the parameter values, almost inevitably in terms of quantitative ranges. These may or may not have been calibrated against the assessing organisation s risk criteria, but the method then becomes semi-quantitative (or is it semi-qualitative It is certainly somewhere between the extremities of the qualitative / quantitative scale.)... 

L. D. Radu, Qualitative, Semi Quantitative and Quantitative Methods for Risk Assessment ... 

Methods and techniques for measurement, sampling, and analysis Types, sources, and characteristics of hazards, threats, and vulnerabilities Hazard analysis, job safety analysis and task analysis methods Qualitative, quantitative, deductive, and inductive risk assessment methods Risk-based decision-making Risk-based decision-making tools... 

In this method risk is evaluated, not by subjective judgement, but by numerical data. Quantitative evaluation of the risk is therefore more demanding than a qualitative approach but provides a more rigorous evaluation. 

HRA is mainly a predictive tool, intended to estimate the probability of human errors and assess the human factors contribution to the overall risk through the use of qualitative and/or quantitative methods. Essentially, traditional HRA tools consist of (i) the identification of potential human erroneous actions, followed by (ii) the consideration of internal and external factors that could influence the human performance, finally resulting in (iii) the... 

Specialized techniques known as risk assessment are created as part of the developing science of safety. They are based on the qualitative, quantitative, semi-quantitative and simulation methods, using control and data acquisition as well as computer databases, operating system based on GIS. 

Risk assessment of hazardous substances transportation may be realized by means of various methods based on qualitative assessment (estimating merely the consequences of accidents) as well as complicated quantitative methods (which, apart from estimating consequences of accidents, determine probability of accident occurrence). 

Assess services, outcomes, methods, equipment, workstations, and procedures by using qualitative and quantitative methods to recognize the hazards and measure the related risks. 

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