A quality engineer at a consumer electronics company wants to know whether the defects per television set are from a Poisson distribution. The engineer randomly selects 300 televisions and records the number of defects per television.
Choose Stat > Basic Statistics > Goodness-of-Fit Test for Poisson.
In Variable, enter Defects.
In Frequency variable: (optional), enter Observed.
Interpret the results
The null hypothesis states that the data follow a Poisson distribution. Because the p-value is 0.000, which is less than the significance level of 0.05, the engineer rejects the null hypothesis and concludes that the data do not follow a Poisson distribution. The graphs indicate that the difference between the observed and expected values is large for categories 1 and 3, and that category 3 is the highest contributor to the chi-square statistic.