week 6 discussion

Errors in Hypothesis Testing

Instructor’s Notes: The discussion is about Type I and Type II errors-see 380-382. Table 9.1 shows this graphically.Very simply though, a Type I error is rejecting the null hypothesis if it’s true and a Type II error is accepting the null hypothesis if it’s false.It is interesting to discussing the circumstances under which each of these errors can occur.

• In §9.2 the concepts of Type I and Type II errors are introduced.
• Now consider the situation where a husband and wife go to the doctor’s office to each get some tests run and the doctor accidently mixes up their charts. The doctor comes into the exam room with the results of the tests and declares that the wife is NOT pregnant but her husband IS indeed pregnant with a baby.
• How does this illustrate the concepts behind Type I and Type II errors?
• With this situation in mind, what type of error (Type I or Type II) is worse? Explain your reasoning.