Production Consider again the task of the quality control inspectors in Exercise 30. 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 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?

Statistical Inference: provides methods for drawing conclusions about a population from the sample data. There are two ways to do this: Confidence intervals: used to estimate the value of a population parameter using sample statistics Test of Significance: used for assessing evidence for a claim about the population To set up Have to have an SRS from the population, no bias The variable has to have an exactly normal distribution in the population We don’t know population mean , but we know the population standard deviation Confidence Interval What statistic can be used to estimate the population parameter o We can use x-bar To do a confidence interval, it is similar to the 68-95-99.7