The poisson test, like the binomial test, is used to determine the probability of an observed frequency. It is used to describe the number of events that will occur in a specific period of time or in a specific area or volume. You need to enter the observed and expected frequencies. It is especially useful to compare the success of a new marketing campagin to previous campaigns.

Example

Previous marketing has shown that an ad placement in a magazine resulted in the sale of 52 products in a one week period. Thus, the expected sales from a ad in one week is 52. A new ad was placed in the same magazine and resulted in the sale of 63 products in a week. What is the probability of selling 63 or more products in a week?

Another example

Previous research on a particular assembly line has shown that they have an average daily defect rate of 39 products. Thus, the expected number of defective products expected on any day is 39. The day after implementing a new quality control program, they found only 25 defects. What is the probability of seeing 25 or fewer defects on any day?