Should I use the binomial, hypergeometric, or Poisson distribution?

By default, Minitab uses the binomial distribution to create sampling plans and compare sampling plans for go/no go data. To correctly use the binomial distribution, Minitab assumes that the sample comes from a large lot (the lot size is at least ten times greater than the sample size) or from a stream of lots randomly selected from an ongoing process. Many of your sampling applications may satisfy this assumption.

However, if the lot of products that you are sampling from is an isolated lot of finite size (for example, you receive one special order shipment of 500 labels) then the exact distribution for calculating the probability of acceptance is the hypergeometric distribution. This application isn't as common as the large lot or continuous lot; however, there are times when you will need to specify the hypergeometric distribution.

Remember, this option is only available when you have go/no go (defectives) data and when you specify the lot size. Minitab uses the Poisson distribution when you count the number of defects.

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