Severity is a key component in risk assessment methodologies like Failure Mode and Effects Analysis (FMEA). It is defined as the seriousness of the effect of a potential failure mode. It quantifies the impact or consequence of a failure on the customer, downstream processes, or the system itself. A higher severity rating indicates a more critical impact, such as a safety hazard or complete loss of function, whereas a lower rating signifies a minor nuisance. Severity is evaluated independently of the likelihood of the failure occurring or being detected.

A. This definition describes Detection, which is an assessment of the ability of current controls to identify the cause or the failure mode before the item reaches the customer.

B. This definition describes Occurrence, which is the likelihood that a specific cause will result in the failure mode during the design life.

C. This is the formal definition of Risk as per the ISO 31000:2018 standard, which is a broader concept than severity. Severity is one component used to evaluate risk.

1. ASQ Quality Press. (2017). The Certified Quality Engineer Handbook (4th ed.). In Chapter 20

"Risk Management

" the FMEA process is detailed. Severity is defined as "an assessment of the seriousness of the effect of the potential failure mode...if it occurs." (p. 298).

2. Automotive Industry Action Group (AIAG) & Verband der Automobilindustrie (VDA). (2019). Failure Mode and Effects Analysis FMEA Handbook (1st ed.). The handbook defines Severity (S) as the "seriousness of the effect" and provides ranking tables based on the impact to the end-user or manufacturing plant. (pp. 37

102).

3. Stamatis

D. H. (2003). Failure Mode and Effect Analysis: FMEA from Theory to Execution (2nd ed.). ASQ Quality Press. The text states

"Severity is the assessment of the seriousness of the effect of the potential failure mode on the next component

subsystem

system

or customer." (p. 55).

4. Purdue University

School of Mechanical Engineering. (n.d.). ME 463

Engineering Design - FMEA Lecture Notes. The course material defines Severity as "a rating of the seriousness of the effect(s) of the potential failure mode." This aligns with the concept of impact.