## [answered] 1. (2 points) To evaluate the efficacy of two different smo

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1.? (2 points) To evaluate the efficacy of two different smoking cessation programs, smokers are randomized to receive either Program A or Program B.? Of the six smokers in Program A, one stopped smoking; of the six smokers in Program B, four stopped smoking.? Which statistical procedure would you use to test the null hypotheses that the programs are equally effective and to obtain a p-value?

????? a.? Paired t-test

????? b.? Chi-square test of independence

????? c.? Two-sample t-test

????? d.? Fisher?s exact test

????? e.? Wilcoxon rank-sum test

2.? (2 points) In a cross sectional study of bicycle helmet use, authors were interested in assessing neighborhood socio-economic status (as measured by percentage of school children receiving free or reduced-fee lunches at school) and percentage of bicycle rider wearing a helmet.? If the assumptions of the test were met, what is the appropriate statistical test to perform:

????? a.? two independent sample t-test

????? b.? Wilcoxon sign-rank test

????? c.? correlation analysis

????? d.? chi-square one-sample test of the variance

????? e.? none of the above

3. (2 points)? A study was performed on 200 elementary school students to investigate whether taking regular Vitamin A supplements during the month of March would prevent colds.? One hundred students were randomized to receive a daily Vitamin A supplement of 3,000 IU and 100 students to receive a placebo.? If you were interested in testing for a statistical relationship between taking Vitamin A and cold status in the population of elementary school students, the correct statistical test is:

????? a.? two independent sample t-test

????? b.? chi-square test of the variance

????? c.? chi-square test of independence (homogeneity)

????? d.? paired t-test

4. (6 points) A researcher wants to determine if an experimental drug significantly affects the body temperature. Seven test subjects are randomly selected and the body temperature of each subject is measured (initial temperature). After that, the subjects are given the drug and after 60 minutes the body temperature of each subject is measured again (follow-up temperature). The results are given in the StatCrunch dataset ?body_temperature_study?. We know that the body temperature is a normally distributed variable.

?Test if the drug significantly affects the body temperature.

- What test will you use?

- State H0 and H1 for this test.

- Provide the p-value and make a final conclusion about the data using the significance level of 0.01.

5. (6 points) A sports psychologist believes that listening to music affects the length of athletes? workout sessions. To test this assumption a random sample of ten athletes was selected. Each athlete had two workouts, one while listening to music and the other without music. For each athlete, each of the two workouts was on a separate day and the order of ?with music? and ?without music? workouts was random. The length of each workout (in minutes) was recorded for each athlete.? The results are given in the StatCrunch dataset ?length_of_workout_epi551?. Assume that the data exhibit significant deviations from normality and the t-test is not applicable.

Test if the psychologist?s claim is justified.

- What test will you use?

- State H0 and H1 for this test.

- Provide the p-value and make a final conclusion about the data using the significance level of 0.05.

6. (6 points) Suppose, you wish to compare salaries in the manufacturing and construction industries. You obtained a random sample of 10 manufacturing workers and another random sample of 10 construction workers. The annual salaries for each individual (in thousands of dollars) are given in the StatCrunch dataset ?comparing_industry_salaries?. Assume that the data exhibit significant deviations from normality and the t-test is not applicable.

Test if the salaries in these two industries are significantly different.

- What test will you use?

- State H0 and H1 for this test.

- Provide the p-value and make a final conclusion about the data using the significance level of 0.01.

1. (2 points) To evaluate the efficacy of two different smoking cessation programs, smokers are

randomized to receive either Program A or Program B. Of the six smokers in Program A, one

stopped smoking; of the six smokers in Program B, four stopped smoking. Which statistical

procedure would you use to test the null hypotheses that the programs are equally effective and

to obtain a p-value?

a. Paired t-test

b. Chi-square test of independence

c. Two-sample t-test

d. Fisher?s exact test

e. Wilcoxon rank-sum test

2. (2 points) In a cross sectional study of bicycle helmet use, authors were interested in assessing

neighborhood socio-economic status (as measured by percentage of school children receiving

free or reduced-fee lunches at school) and percentage of bicycle rider wearing a helmet. If the

assumptions of the test were met, what is the appropriate statistical test to perform:

a. two independent sample t-test

b. Wilcoxon sign-rank test

c. correlation analysis

d. chi-square one-sample test of the variance

e. none of the above

3. (2 points) A study was performed on 200 elementary school students to investigate whether

taking regular Vitamin A supplements during the month of March would prevent colds. One

hundred students were randomized to receive a daily Vitamin A supplement of 3,000 IU and 100

students to receive a placebo. If you were interested in testing for a statistical relationship

between taking Vitamin A and cold status in the population of elementary school students, the

correct statistical test is:

a. two independent sample t-test

b. chi-square test of the variance

c. chi-square test of independence (homogeneity)

d. paired t-test

4. (6 points) A researcher wants to determine if an experimental drug significantly affects

the body temperature. Seven test subjects are randomly selected and the body temperature

of each subject is measured (initial temperature). After that, the subjects are given the drug

and after 60 minutes the body temperature of each subject is measured again (follow-up

temperature). The results are given in the StatCrunch dataset ?body_temperature_study?.

We know that the body temperature is a normally distributed variable.

Test if the drug significantly affects the body temperature.

- What test will you use?

- State H0 and H1 for this test. - Provide the p-value and make a final conclusion about the data using the significance level of

0.01.

5. (6 points) A sports psychologist believes that listening to music affects the length of

athletes? workout sessions. To test this assumption a random sample of ten athletes was

selected. Each athlete had two workouts, one while listening to music and the other without

music. For each athlete, each of the two workouts was on a separate day and the order of

?with music? and ?without music? workouts was random. The length of each workout (in

minutes) was recorded for each athlete. The results are given in the StatCrunch dataset

?length_of_workout_epi551?. Assume that the data exhibit significant deviations from

normality and the t-test is not applicable.

Test if the psychologist?s claim is justified.

- What test will you use?

- State H0 and H1 for this test.

- Provide the p-value and make a final conclusion about the data using the significance level of

0.05.

6. (6 points) Suppose, you wish to compare salaries in the manufacturing and construction

industries. You obtained a random sample of 10 manufacturing workers and another

random sample of 10 construction workers. The annual salaries for each individual (in

thousands of dollars) are given in the StatCrunch dataset ?comparing_industry_salaries?.

Assume that the data exhibit significant deviations from normality and the t-test is not

applicable.

Test if the salaries in these two industries are significantly different.

- What test will you use?

- State H0 and H1 for this test.

- Provide the p-value and make a final conclusion about the data using the significance level of

0.01.

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