METHODS FOR COMPONENT RELIABILITY ANALYSIS by

A random variable, X, is a variable described by a probability distri-bution. The distribution specifies the chance that an observation, x, of the variable will fall in a speafied range of X A set of observations, xi, XL..., x, of the random variable, X, is called a sample. It i s assumed that samples are drawn'from a population (gen-erally unknown) possessing constant statistical properties while the properties of a sample may vary from one sample to another. The possible range of variation of all of the samples which could be drawn from the population is called the sample space, and an event is a subset of the sample space. The probability of an event, P(A), is the chance that it will occur when an observation of the random variable is made. Probabilities of events can be estimated. If a sample of n observations has nA values in the range of event A, then the relative frequency of the occurrence of A is nA/n and, as the sample size is increased, the relative frequency becomes