6. Fish law

When the probability p of obtaining a defective part is low, the pseudo-curve representing Bernoulli's law has a characteristic appearance: the probability of finding zero or a very small number of defective parts in the sample is high (figure 7 ). A simpler, single-parameter law leads to the same numerical values as Bernoulli's law: this is Poisson's law. It is defined by : $P\left(k\right)={\text{e}}^{-\nu }\frac{{\nu }^k}{k!}$

ν is called the parameter of the Poisson distribution.

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