[Seniorita]

Ch 15

J2. In formulating hypotheses for a statistical test of significance, the null hypothesis is often

K2. In their advertisements, the manufacturers of a certain brand of oatmeal would like to claim that eating their oatmeal for breakfast daily will produce a mean decrease in cholesterol of more than 10 points in one month for people with cholesterol levels over 200. In order to determine if this is a valid claim, they hire an independent testing agency, which then selects 25 people with a cholesterol level over 200 to eat their oatmeal for breakfast daily for a month. The agency should be testing the null hypothesis H0: m = 10 and the alternative hypothesis

L2. Suppose we are testing the null hypothesis H0: m = 20 and the alternative Ha: m 20, for a normal population with s = 6. A random sample of nine observations are drawn from the population, and we find the sample mean of these observations is = 17. The P-value is closest to

M2. The mean area m of the several thousand apartments in a new development by a certain builder is advertised to be 1250 square feet. A tenant group thinks this is inaccurate, because it is based on the square footage of apartments in an older development by the same builder. The group hires an engineer to measure a sample of apartments to verify its suspicion. The appropriate null and alternative hypotheses, H0 and Ha, for m are

N2. Is the mean age at which American children can first read now under 4 years? If the population of all American children has mean age of m years until they begin to read and standard deviation s years, one would test which of the following null and alternative hypotheses to answer this question?

The Survey of Study Habits and Attitudes (SSHA) is a psychological test that measures the motivation, attitudes, and study habits of college students. Scores range from 0 to 200 and follow (approximately) a normal distribution, with mean of 115 and standard deviation s = 25. You suspect that incoming freshman have a mean m, which is different from 115, because they are often excited yet anxious about entering college. To verify your suspicion, you test the hypotheses
H0: m = 115, Ha: m 115.

O2 You give the SSHA to 25 students who are incoming freshman and find their mean score. Assuming that the scores of all incoming freshmen are approximately normal, with the same standard deviation as the scores of all college students, the P-value of the test of the null hypothesis is

P2. The Survey of Study Habits and Attitudes (SSHA) is a psychological test that measures the motivation, attitudes, and study habits of college students. Scores range from 0 to 200 and follow (approximately) a normal distribution, with mean of 115 and standard deviation s = 25. You suspect that incoming freshman have a mean m, which is different from 115, because they are often excited yet anxious about entering college. To verify your suspicion, you test the hypotheses
H0: m = 115, Ha: m 115.

In testing these hypotheses, which of the following would be strong evidence against the null hypothesis?


Q2. In a statistical test of hypotheses, we say the data are statistically significant at level a if

R2. In a test of statistical hypotheses, the P-value tells us

S2. A university administrator obtains a sample of the academic records of past and present scholarship athletes at the university. The administrator reports that no significant difference was found in the mean GPA (grade point average) for male and female scholarship athletes (P = 0.287). This means


Ch 16

Use the following to answer questions t2-u2
A researcher wishes to determine if aerobic exercise improves mental performance immediately following the exercise. He plans to have high school students participate in 30 minutes of aerobic exercise and then take a standard test of their reasoning skills. Suppose the scores of high school students on this test of reasoning skills immediately after 30 minutes of aerobic exercise follow a normal distribution, with mean m and standard deviation s = 4. Suppose also, that in the general population of all high school students, scores on the test of reasoning skills follow a normal distribution, with mean 25 and standard deviation s = 4. The researcher, therefore, decides to test the hypotheses

H0: m = 25, Ha: m > 25.

To do so, the researcher has 10,000 high school students do 30 minutes of aerobic exercise and then, immediately following the exercise, take the test. The mean score for these students is = 25.2 and the P-value is less than 0.0001.

T2. It is appropriate to conclude which of the following?

U2. Suppose that two high school students decide to see if they get the same results as the researcher. They both do 30 minutes of aerobic exercise and, immediately following the exercise, take the test. The mean of their scores is = 25.2 seconds, the same as that of the researcher. It is appropriate to conclude which of the following?

V2. In testing hypotheses, if the consequences of rejecting the null hypothesis are very serious, we should

. The Survey of Study Habits and Attitudes (SSHA) is a psychological test that measures the motivation, attitudes, and study habits of college students. Scores range from 0 to 200 and follow (approximately) a normal distribution with mean 115 and standard deviation s = 25. You suspect that incoming freshman have a mean m, which is different from 115, since they are often excited yet anxious about entering college. To verify your suspicion, you test the hypotheses

H0: m = 115, Ha: m 115X

W2 You give the SSHA to 25 incoming freshman and find their mean score. Based on this, you reject H0 at significance level a = 0.01. Which of the following would be most helpful in assessing the practical significance of your results?

Y2. A medical researcher is working on a new treatment for a certain type of cancer. The average survival time after diagnosis on the standard treatment is two years. In an early trial, she tries the new treatment on three subjects who have an average survival time after diagnosis of four years. Although the survival time has doubled, the results are not statistically significant even at the 0.10 significance level. The explanation is

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