## 3 Materials and Methods
### Using the Extended RPI to Propose a Qualitative Mitigation Index (QMI)  
The risk assessment of a particular failure mode must be performed while considering the possibilities to avoid or mitigate the same failure mode depending on the particular risk scenario and the available resources. In the traditional FMEA, the detectability risk variable aims to correct the critical value resulting from the multiplication of severity and occurrence. However, detectability depends on several factors, such as available resources and knowledge, which may vary depending on the capabilities of the risk owners. Therefore, detectability can be considered as a mitigation-based risk variable that updates the risk level according to the available capabilities to detect failure modes. To illustrate the impact of mitigation performance on risk impact, please consider the following example:  
In the last century, the risk of hospital-acquired infections was dramatically reduced when it was discovered that handwashing prevents the spread of disease. So, in this risk scenario, the risk of spreading a particular disease depended heavily on the knowledge that handwashing prevents spread and the ability to put that knowledge into practice. These two cornerstones, knowledge and the ability to put knowledge into practice, can be considered as mitigation variables in this risk scenario that can be used to assess performance in preventing the spread of disease, and thus update the risk level of a given risk scenario. To extend the concept of risk mitigation variables to generic risk scenarios, reliability, availability, resilience, and robustness are proposed as generic risk mitigation variables to evaluate the performance level of risk mitigation in a given risk scenario. These four risk mitigation variables are generic enough to be applied to any risk scenario, as is the case with the severity, occurrence, and detectability risk variables. Despite their broad scope, they can be easily evaluated in the context of risk scenarios. There are many definitions of reliability, usually varying by discipline, but all are synonymous with the following: _\"Reliability is the ability to perform consistently well over an expected period of time\"_. Thus, to evaluate this risk mitigation variable within a risk scenario with a qualitative approach and using a rating scale of, say, 1 to 10, one can answer the following question based on the resources available and the scope of the risk scenario:  
* _Do I have the required knowledge, information and experience to perform consistently well and maintain the required level of quality to avoid/mitigate the analyzed failure mode_? This question can be used to assess the ability to do a good job, but not the availability of that ability. In this sense, availability is defined here as a mitigation variable and can be evaluated as an answer to the following question:  
* _Given the available resources, do I have the necessary human and technical resources to avoid the analyzed failure mode_? In many cases, unexpected events occur that lower the overall level of risk mitigation capability, especially for the reliability and availability mitigation variables. One way to minimize or eliminate their impact is to detect or predict these events before they actually occur. This gives the time needed to make the necessary changes. It is also necessary to consider the time it takes to respond to an identified mitigation performance issue. So, resilience is a variable of mitigation performance that can be used here to measure these concepts, and its rating can be determined by answering the following question:  
* _Am I able to recover the level of reliability and available performance when adverse events occur and make the necessary changes within an acceptable period of time_?One would think that these three mitigation variables (reliability, availability, and resilience) can be evaluated based on ideal assumptions that are usually taken for granted in the traditional FMEA approach, but this is not true.