Question: Production. Consider again the task of the quality control inspectors in Exercise.

a) In this context, what is meant by the power of the test the inspectors conduct?

b) They are currently testing 5 items each hour. Someone has proposed that they test 10 each hour instead. What are the advantages and disadvantages of such a change?

c) Their test currently uses a 5% level of significance. What are the advantages and disadvantages of changing to an alpha level of 1%?

d) Suppose that, as a day passes, one of the machines on the assembly line produces more and more items that are defective. How will this affect the power of the test?

Exercise: Quality control. Production managers on an assembly line must monitor the output to be sure that the level of defective products remains small. They periodically inspect a random sample of the items produced. If they find a significant increase in the proportion of items that must be rejected, they will halt the assembly process until the problem can be identified and repaired.

a) In this context, what is a Type I error?

b) In this context, what is a Type II error?

c) Which type of error would the factory owner consider more serious?

d) Which type of error might customers consider more serious?