The reliability of an item or a system can be think, as a first approach, as the probability that the device or the system will adequately perform the specified function for a well-defined time interval in specified environmental conditions. Starting from this first definition it is well clear the importance of the probability and statistics science in both reliability definition and evaluation. This chapter is devoted to introduce some important probability and statistics concepts necessary for reliability evaluation. In particular, the statistical point of view is developed and discussed as a first approach to dependability feature of a system or device. A brief overview on probability and statistics concepts is given in the first pages of this chapter. In particular, in 2.2.1 the axioms of probability are given and the law of the large number is discussed in 2.2.2. Random variables are introduced in 2.3 and probability distributions are detailed in 2.4. Finally, the reliability function is derived. Furthermore, it is defined the concept of the failure rate model in section 2.7. In 2.8 the more used distribution laws are discussed.
KeywordsFailure Rate Probability Density Function Weibull Distribution Sample Space Reliability Function
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