CAIE S2 2017 November — Question 6

Exam BoardCAIE
ModuleS2 (Statistics 2)
Year2017
SessionNovember
TopicHypothesis test of a Poisson distribution

6 In a certain factory the number of items per day found to be defective has had the distribution \(\operatorname { Po } ( 1.03 )\). After the introduction of new quality controls, the management wished to test at the \(10 \%\) significance level whether the mean number of defective items had decreased. They noted the total number of defective items produced in 5 randomly chosen days. It is assumed that defective items occur randomly and that a Poisson model is still appropriate.
  1. Given that the total number of defective items produced during the 5 days was 2 , carry out the test.
  2. Using another random sample of 5 days the same test is carried out again, with the same significance level. Find the probability of a Type I error.
  3. Explain what is meant by a Type I error in this context.