Editing Failure rate (section)

{{short description|Frequency with which an engineered system or component fails}}
'''Failure rate''' is the [[frequency]] with which any system or component fails, expressed in failures per unit of time. It thus depends on the system conditions, time interval, and total number of systems under study.<ref name='macdiarmid'>*
{{cite book |last1=MacDiarmid |first1=Preston |last2=Morris |first2=Seymour |date=n.d. |title=Reliability Toolkit |edition=Commercial Practices |pages=35–39 |publisher=Reliability Analysis Center and Rome Laboratory |location=Rome, New York |display-authors=etal}}</ref>
It can describe electronic, mechanical, or biological systems, in fields such as [[systems engineering|systems]] and [[reliability engineering|reliability]] engineering, [[medicine]] and [[biology]], or [[insurance]] and [[finance]]. It is usually denoted by the [[Greek alphabet|Greek letter]] <math>\lambda</math> ([[lambda]]).

In real-world applications, the failure probability of a system usually differs over time; failures occur more frequently in early-life ([[Burn-in|"burning in"]]), or as a system ages ([[Wear and tear|"wearing out"]]). This is known as the [[bathtub curve]], where the middle region is called the "useful life period".