Risk Assessment and Analysis Methods: Qualitative and Quantitative

A risk assessment determines the likelihood, consequences and tolerances of possible incidents. “Risk assessment is an inherent part of a broader risk management strategy to introduce control measures to eliminate or reduce any potential risk- related consequences.” 1 The main purpose of risk assessment is to avoid negative consequences related to risk or to evaluate possible opportunities.

It is the combined effort of:

• “…[I]dentifying and analyzing possible future events that could adversely affect individuals, assets, processes and/or the environment (i.e.,risk analysis)”

• “…[M]aking judgments about managing and tolerating risk on the basis of a risk analysis while considering influencing factors (i.e., risk evaluation)” 2

Relationships between assets, processes, threats, vulnerabilities and other factors are analyzed in the risk assessment approach. There are many methods available, but quantitative and qualitative analysis are the most widely known and used classifications. In general, the methodology chosen at the beginning of the decision-making process should be able to produce a quantitative explanation about the impact of the risk and security issues along with the identification of risk and formation of a risk register. There should also be qualitative statements that explain the importance and suitability of controls and security measures to minimize these risk areas. 3

In general, the risk management life cycle includes seven main processes that support and complement each other (figure 1):

1. Determine the risk context and scope, then design the risk management strategy.
2. Choose the responsible and related partners, identify the risk and prepare the risk registers.
3. Perform qualitative risk analysis and select the risk that needs detailed analysis.
4. Perform quantitative risk analysis on the selected risk.
5. Plan the responses and determine controls for the risk that falls outside the risk appetite.
6. Implement risk responses and chosen controls.
7. Monitor risk improvements and residual risk.

Qualitative and Quantitative Risk Analysis Techniques

Different techniques can be used to evaluate and prioritize risk. Depending on how well the risk is known, and if it can be evaluated and prioritized in a timely manner, it may be possible to reduce the possible negative effects or increase the possible positive effects and take advantage of the opportunities. 4 “Quantitative risk analysis tries to assign objective numerical or measurable values” regardless of the components of the risk assessment and to the assessment of potential loss. Conversely, “a qualitative risk analysis is scenario-based.” 5

Qualitative Risk
The purpose of qualitative risk analysis is to identify the risk that needs detail analysis and the necessary controls and actions based on the risk’s effect and impact on objectives. 6 In qualitative risk analysis, two simple methods are well known and easily applied to risk: 7

1. Keep It Super Simple (KISS)—This method can be used on narrow-framed or small projects where unnecessary complexity should be avoided and the assessment can be made easily by teams that lack maturity in assessing risk. This one-dimensional technique involves rating risk on a basic scale, such as very high/high/medium/low/very.
2. Probability/Impact—This method can be used on larger, more complex issues with multilateral teams that have experience with risk assessments. This two-dimensional technique is used to rate probability and impact. Probability is the likelihood that a risk will occur. The impact is the consequence or effect of the risk, normally associated with impact to schedule, cost, scope and quality. Rate probability and impact using a scale such as 1 to 10 or 1 to 5, where the risk score equals the probability multiplied by the impact.

Qualitative risk analysis can generally be performed on all business risk. The qualitative approach is used to quickly identify risk areas related to normal business functions. The evaluation can assess whether peoples’ concerns about their jobs are related to these risk areas. Then, the quantitative approach assists on relevant risk scenarios, to offer more detailed information for decision-making. 8 Before making critical decisions or completing complex tasks, quantitative risk analysis provides more objective information and accurate data than qualitative analysis. Although quantitative analysis is more objective, it should be noted that there is still an estimate or inference. Wise risk managers consider other factors in the decision-making process. 9

Although a qualitative risk analysis is the first choice in terms of ease of application, a quantitative risk analysis may be necessary. After qualitative analysis, quantitative analysis can also be applied. However, if qualitative analysis results are sufficient, there is no need to do a quantitative analysis of each risk.

Quantitative Risk
A quantitative risk analysis is another analysis of high-priority and/or high-impact risk, where a numerical or quantitative rating is given to develop a probabilistic assessment of business-related issues. In addition, quantitative risk analysis for all projects or issues/processes operated with a project management approach has a more limited use, depending on the type of project, project risk and the availability of data to be used for quantitative analysis. 10

The purpose of a quantitative risk analysis is to translate the probability and impact of a risk into a measurable quantity. 11 A quantitative analysis: 12

• “Quantifies the possible outcomes for the business issues and assesses the probability of achieving specific business objectives”
• “Provides a quantitative approach to making decisions when there is uncertainty”
• “Creates realistic and achievable cost, schedule or scope targets”

Consider using quantitative risk analysis for: 13

• “Business situations that require schedule and budget control planning”
• “Large, complex issues/projects that require go/no go decisions”
• “Business processes or issues where upper management wants more detail about the probability of completing on schedule and within budget”

The advantages of using quantitative risk analysis include: 14

• Objectivity in the assessment
• Powerful selling tool to management
• Direct projection of cost/benefit
• Flexibility to meet the needs of specific situations
• Flexibility to fit the needs of specific industries
• Much less prone to arouse disagreements during management review
• Analysis is often derived from some irrefutable facts

THE MOST COMMON PROBLEM IN QUANTITATIVE ASSESSMENT IS THAT THERE IS NOT ENOUGH DATA TO BE ANALYZED.

To conduct a quantitative risk analysis on a business process or project, high-quality data, a definite business plan, a well-developed project model and a prioritized list of business/project risk are necessary. Quantitative risk assessment is based on realistic and measurable data to calculate the impact values that the risk will create with the probability of occurrence. This assessment focuses on mathematical and statistical bases and can “express the risk values in monetary terms, which makes its results useful outside the context of the assessment (loss of money is understandable for any business unit). 15 The most common problem in quantitative assessment is that there is not enough data to be analyzed. There also can be challenges in revealing the subject of the evaluation with numerical values or the number of relevant variables is too high. This makes risk analysis technically difficult.

There are several tools and techniques that can be used in quantitative risk analysis. Those tools and techniques include: 16

• Heuristic methods—Experience-based or expert- based techniques to estimate contingency
• Three-point estimate—A technique that uses the optimistic, most likely and pessimistic values to determine the best estimate
• Decision tree analysis—A diagram that shows the implications of choosing various alternatives
• Expected monetary value(EMV)—A method used to establish the contingency reserves for a project or business process budget and schedule
• Monte Carlo analysis—A technique that uses optimistic, most likely and pessimistic estimates to determine the business cost and project completion dates
• Sensitivity analysis—A technique used to determine the risk that has the greatest impact on a project or business process
• Fault tree analysis (FTA) and failure modes andeffects analysis (FMEA)—The analysis of a structured diagram that identifies elements that can cause system failure

There are also some basic (target, estimated or calculated) values used in quantitative risk assessment. Single loss expectancy (SLE) represents the money or value expected to be lost if the incident occurs one time, and an annual rate of occurrence (ARO) is how many times in a one-year interval the incident is expected to occur. The annual loss expectancy (ALE) can be used to justify the cost of applying countermeasures to protect an asset or a process. That money/value is expected to be lost in one year considering SLE and ARO. This value can be calculated by multiplying the SLE with the ARO. 17 For quantitative risk assessment, this is the risk value. 18

USING BOTH APPROACHES CAN IMPROVE PROCESS EFFICIENCY AND HELP ACHIEVE DESIRED SECURITY LEVELS.

By relying on factual and measurable data, the main benefits of quantitative risk assessment are the presentation of very precise results about risk value and the maximum investment that would make risk treatment worthwhile and profitable for the organization. For quantitative cost-benefit analysis, ALE is a calculation that helps an organization to determine the expected monetary loss for an asset or investment due to the related risk over a single year.

For example, calculating the ALE for a virtualization system investment includes the following:

• Virtualization system hardware value: US$1 million (SLE for HW)
• Virtualization system management software value: US$250,000 (SLE for SW)
• Vendor statistics inform that a system catastrophic failure (due to software or hardware) occurs one time every 10 years (ARO = 1/10 = 0.1)
• ALE for HW = 1M * 1 = US$100,000
• ALE for SW = 250K * 0.1 = US$25,000

In this case, the organization has an annual risk of suffering a loss of US$100,000 for hardware or US$25,000 for software individually in the event of the loss of its virtualization system. Any implemented control (e.g., backup, disaster recovery, fault tolerance system) that costs less than these values would be profitable.

Some risk assessment requires complicated parameters. More examples can be derived according to the following “step-by-step breakdown of the quantitative risk analysis”: 19

1. Conduct a risk assessment and vulnerability study to determine the risk factors.
2. Determine the exposure factor (EF), which is the percentage of asset loss caused by the identified threat.
3. Based on the risk factors determined in the value of tangible or intangible assets under risk, determine the SLE, which equals the asset value multiplied by the exposure factor.
4. Evaluate the historical background and business culture of the institution in terms of reporting security incidents and losses (adjustment factor).
5. Estimate the ARO for each risk factor.
6. Determine the countermeasures required to overcome each risk factor.
7. Add a ranking number from one to 10 for quantifying severity (with 10 being the most severe) as a size correction factor for the risk estimate obtained from company risk profile.
8. Determine the ALE for each risk factor. Note that the ARO for the ALE after countermeasure implementation may not always be equal to zero. ALE (corrected) equals ALE (table) times adjustment factor times size correction.
9. Calculate an appropriate cost/benefit analysis by finding the differences before and after the implementation of countermeasures for ALE.
10. Determine the return on investment (ROI) based on the cost/benefit analysis using internal rate of return (IRR).
11. Present a summary of the results to management for review.

Using both approaches can improve process efficiency and help achieve desired security levels. In the risk assessment process, it is relatively easy to determine whether to use a quantitative or a qualitative approach. Qualitative risk assessment is quick to implement due to the lack of mathematical dependence and measurements and can be performed easily. Organizations also benefit from the employees who are experienced in asset/processes; however, they may also bring biases in determining probability and impact. Overall, combining qualitative and quantitative approaches with good assessment planning and appropriate modeling may be the best alternative for a risk assessment process (figure 2). 20

Conclusion

Qualitative risk analysis is quick but subjective. On the other hand, quantitative risk analysis is optional and objective and has more detail, contingency reserves and go/no-go decisions, but it takes more time and is more complex. Quantitative data are difficult to collect, and quality data are prohibitively expensive. Although the effect of mathematical operations on quantitative data are reliable, the accuracy of the data is not guaranteed as a result of being numerical only. Data that are difficult to collect or whose accuracy is suspect can lead to inaccurate results in terms of value. In that case, business units cannot provide successful protection or may make false-risk treatment decisions and waste resources without specifying actions to reduce or eliminate risk. In the qualitative approach, subjectivity is considered part of the process and can provide more flexibility in interpretation than an assessment based on quantitative data. 21

For a quick and easy risk assessment, qualitative assessment is what 99 percent of organizations use. However, for critical security issues, it makes sense to invest time and money into quantitative risk assessment. 22 By adopting a combined approach, considering the information and time response needed, with data and knowledge available, it is possible to enhance the effectiveness and efficiency of the risk assessment process and conform to the organization’s requirements.