ABSTRACT
Upon surveying the distributions examined in this book, the reader is apt to seek
answers to the question, Given a data set, what distribution model should one use
to fit the data? To assist the analyst in this area, formal procedures for testing the
goodness-of-fit of a particular distribution are introduced. However, the efficiency
of such procedures is limited. As such, reliability professionals usually settle for
the use of one or two distribution models that make sense for the kind of data they
see in their industry. For example, reliability engineers who work with mechanical
systems often make use of a Weibull distribution for modeling wearout phenom-
ena. This is not exclusively true, as others, depending on their specific industry or
company, make use of the lognormal distribution. On the other hand, reliability
engineers who work in the electronics industry often rely on the exponential
distribution for modeling time-to-failure phenomena. This has begun to change in
certain segments of the electronics industry that have started to use distributions
such as the Weibull for modeling time-dependent hazard rates.
