Читать книгу Design for Excellence in Electronics Manufacturing - Cheryl Tulkoff - Страница 42

The binomial distribution is used when there are only two possible outcomes: success/fail, go/no go, good/bad. Random experiments with success or failure outcomes are often referred to as Bernoulli trials. For the analysis to be valid, the trials must be independent, and the probability of success for each trial remains constant. The distribution is very useful in reliability and quality work and can model the probability of getting X good items in a sample of Y items. The Poisson distribution is used to model rates of events that occur at a constant average rate with only one of two outcomes countable. It models the number of failures in a given time and describes the distribution of isolated events in a large population. As an example, if the average number of defective units per year per 10,000 units is 0.05, you can evaluate the probabilities of zero, one, two or more faults occurring in a 5‐, 10‐, or 15‐year period.