Discussion:
Q1) A consumer advocacy group is doing a large study on car rental practices. Among other things, the consumer group would like to do a statistical test regarding the mean monthly mileage of cars rented in the U.S. this year. The consumer group has reason to believe that the mean monthly mileage of cars rented in the U.S. this year is different from last year's mean, which was 2700 miles.
The group plans to do a statistical test regarding the value of (mean). It chooses a random sample of monthly mileages and computes the mean of the sample to be 2800 miles and the standard deviation to be 700 miles.
Based on this information, answer the questions below.
- What are the null hypothesis (Ho) and the alternate hypothesis (H1) that should be used for the test?
- In the context of this test, what is a Type ll error? (rejecting or failing to reject)
- Suppose the group decides to reject the null hypothesis. What sort of error might it be making? (Type I or Type II)
Q2) A researcher studying stress is interested in the blood pressure measurements of chief executive officers (CEOs) of major corporations. He believes that the mean systolic blood pressure (mean), of CEOs of major corporations is less than 136 mm Hg, which is the value reported in a possibly outdated journal article. He plans to perform a statistical test. He measures the systolic blood pressures of a random sample of CEOs of major corporations and finds the mean of the sample to be 130 mm Hg and the standard deviation of the sample to be 18 mm Hg.
Based on this information, response the questions below.
- What are the null hypothesis (Ho) and the alternate hypothesis (H1) that should be used for the test?
- In the context of this test, what is a Type ll error? (rejecting or failing to reject)
- Suppose the researcher decides not to reject the null hypothesis. What sort of error might it be making? (Type I or Type II)