Slide 20 - 1 Copyright © 2009 Pearson Education, Inc. Active Learning Lecture Slides For use with Classroom Response Systems Intro Stats Third Edition

Slide 20 - 1Copyright © 2009 Pearson Education, Inc.

Active Learning Lecture Slides For use with Classroom Response Systems

Intro Stats Third Edition

by De Veaux, Velleman, Bock

Chapter 20: Testing Hypotheses About Proportions


A P-value indicates

A. the probability that the null hypothesis is true.

B. the probability that the alternative hypothesis is true.

C. the probability of the observed statistic given that the null hypothesis is true.

D. the probability of the observed statistic given that the alternative hypothesis is true.


A P-value indicates

A. the probability that the null hypothesis is true.

B. the probability that the alternative hypothesis is true.

C. the probability of the observed statistic given that the null hypothesis is true.

D. the probability of the observed statistic given that the alternative hypothesis is true.


A small P-value indicates either that the observation is improbable or that the probability calculation was based on incorrect assumptions.

A. True

B. False


A small P-value indicates either that the observation is improbable or that the probability calculation was based on incorrect assumptions.

A. True

B. False


In a hypothesis test, we check the Success/Failure Condition with the observed proportions.

A. True

B. False


In a hypothesis test, we check the Success/Failure Condition with the observed proportions.

A. True

B. False


In a hypothesis test, the null hypothesis represents the status quo.

A. True

B. False


In a hypothesis test, the null hypothesis represents the status quo.

A. True

B. False


According to a June 2004 Gallup poll, 28% of Americans “said there have been times in the last year when they haven’t been able to afford medical care.” Is this proportion higher for black Americans than for all Americans? In a random sample of 801 black Americans, 38% reported that there had been times in the last year when they had not been able to afford medical care. Which type of hypothesis test would you use?

A. One-tail upper tail

B. One-tail lower tail

C. Two-tail

D. Both A and B


According to a June 2004 Gallup poll, 28% of Americans “said there have been times in the last year when they haven’t been able to afford medical care.” Is this proportion higher for black Americans than for all Americans? In a random sample of 801 black Americans, 38% reported that there had been times in the last year when they had not been able to afford medical care. Which type of hypothesis test would you use?

A. One-tail upper tail

B. One-tail lower tail

C. Two-tail

D. Both A and B


A statistics professor wants to see if more than 80% of her students enjoyed taking her class. At the end of the term, she takes a random sample of students from her large class and asks, in an anonymous survey, if the students enjoyed taking her class. Which set of hypotheses should she test?

A. H0: p < 0.80 HA: p > 0.80

B. H0: p = 0.80 HA: p > 0.80

C. H0: p > 0.80 HA: p = 0.80

D. H0: p = 0.80 HA: p < 0.80


A statistics professor wants to see if more than 80% of her students enjoyed taking her class. At the end of the term, she takes a random sample of students from her large class and asks, in an anonymous survey, if the students enjoyed taking her class. Which set of hypotheses should she test?

A. H0: p < 0.80 HA: p > 0.80

B. H0: p = 0.80 HA: p > 0.80

C. H0: p > 0.80 HA: p = 0.80

D. H0: p = 0.80 HA: p < 0.80


An online catalog company wants on-time delivery for 90% of the orders they ship. They have been shipping orders via UPS and FedEx but will switch to a new, cheaper delivery service (ShipFast) unless there is evidence that this service cannot meet the90% on-time goal. As a test the company sends a random sample of orders via ShipFast, and then makes follow-up phone calls to see if these orders arrived on time. Which hypotheses should they test?

A. H0: p < 0.90 HA: p > 0.90

B. H0: p = 0.90 HA: p > 0.90

C. H0: p > 0.90 HA: p = 0.90

D. H0: p = 0.90 HA: p < 0.90


An online catalog company wants on-time delivery for 90% of the orders they ship. They have been shipping orders via UPS and FedEx but will switch to a new, cheaper delivery service (ShipFast) unless there is evidence that this service cannot meet the90% on-time goal. As a test the company sends a random sample of orders via ShipFast, and then makes follow-up phone calls to see if these orders arrived on time. Which hypotheses should they test?

A. H0: p < 0.90 HA: p > 0.90

B. H0: p = 0.90 HA: p > 0.90

C. H0: p > 0.90 HA: p = 0.90

D. H0: p = 0.90 HA: p < 0.90





Chapter 21: More About Tests


The threshold P-value that determines when we reject a null hypothesis is called the

A. alpha value.

B. power.

C. beta value.

D. level of significance.


The threshold P-value that determines when we reject a null hypothesis is called the

A. alpha value.

B. power.

C. beta value.

D. level of significance.


We commit a Type II error when the null hypothesis is true, but we mistakenly reject it.

A. True

B. False


We commit a Type II error when the null hypothesis is true, but we mistakenly reject it.

A. True

B. False


Suppose that a manufacturer is testing one of its machines to make sure that the machine is producing more than 97% good parts (H0: p = 0.97 and HA: p >0.97). The test results in a P-value of 0.102. In reality, the machine is producing 99% good parts. What probably happens as a result of our testing?

A. We correctly fail to reject H0.

B. We correctly reject H0.

C. We reject H0, making a Type I error.

D. We fail to reject H0, making a Type I error.

E. We fail to reject H0, making a Type II error.


Suppose that a manufacturer is testing one of its machines to make sure that the machine is producing more than 97% good parts (H0: p = 0.97 and HA: p >0.97). The test results in a P-value of 0.102. In reality, the machine is producing 99% good parts. What probably happens as a result of our testing?

A. We correctly fail to reject H0.

B. We correctly reject H0.


D. We fail to reject H0, making a Type I error.

E. We fail to reject H0, making a Type II error.


Which of the following is true about Type I and Type II errors?

I. Type I errors are always worse than Type II errors.

II. Type II errors are always worse than Type I errors.

III. The severity of Type I and Type II errors depends on the situation being tested.

A. I only

B. II only

C. III only

D. I and II


Which of the following is true about Type I and Type II errors?

I. Type I errors are always worse than Type II errors.

II. Type II errors are always worse than Type I errors.

III. The severity of Type I and Type II errors depends on the situation being tested.

A. I only

B. II only

C. III only

D. I and II


We are about to test a hypothesis using data from a well-designed study. Which is true?I. A large P-value would be strong evidence against

the null hypothesis.

II. We can set a higher standard of proof by choosing α = 10% instead of 5%.

III. If we reduce the risk of committing a Type I error, then the risk of a Type II error will also decrease.

A) None

B) I only

C) II only

D) III only

E) I and II only


We are about to test a hypothesis using data from a well-designed study. Which is true?I. A large P-value would be strong evidence against

the null hypothesis.

II. We can set a higher standard of proof by choosing α = 10% instead of 5%.

III. If we reduce the risk of committing a Type I error, then the risk of a Type II error will also decrease.

A) None

B) I only

C) II only

D) III only

E) I and II only


Suppose that a device advertised to increase a car’s gas mileage really does not work. We test it on a small fleet of cars (with H0: not effective), and our data results in a P-value of 0.004. What probably happens as a result of our experiment?

A. We correctly fail to reject H0 .

B. We correctly reject H0 .


D. We reject H0, making a Type II error.

E. We fail to reject H0, committing Type II error.


Suppose that a device advertised to increase a car’s gas mileage really does not work. We test it on a small fleet of cars (with H0: not effective), and our data results in a P-value of 0.004. What probably happens as a result of our experiment?

A. We correctly fail to reject H0 .

B. We correctly reject H0 .


D. We reject H0, making a Type II error.

E. We fail to reject H0, committing Type II error.


We will test the hypothesis that p = 60% versus p > 60%. We don’t know it, but actually p is 70%. With which sample size and significance level will our test have the greatest power?

A. α = 0.01, n = 200

B. α = 0.01, n = 500

C. α = 0.05, n = 200

D. α = 0.05, n = 500


We will test the hypothesis that p = 60% versus p > 60%. We don’t know it, but actually p is 70%. With which sample size and significance level will our test have the greatest power?

A. α = 0.01, n = 200

B. α = 0.01, n = 500

C. α = 0.05, n = 200

D. α = 0.05, n = 500





Chapter 22: Comparing Two Proportions


Great Britain has a great literary tradition that spans centuries. One might assume, then, that Britons read more than citizens of other countries. Some Canadians, however, feel that a higher percentage of Canadians than Britons read. A recent Gallup Poll reported that 86% of 1004 randomly sampled Canadians read at least one book in the past year, compared to 81% of 1009 randomly sampled Britons. If we compare proportions of Britons and Canadians who read books, the 10% Condition is fulfilled.

A. True

B. False


Great Britain has a great literary tradition that spans centuries. One might assume, then, that Britons read more than citizens of other countries. Some Canadians, however, feel that a higher percentage of Canadians than Britons read. A recent Gallup Poll reported that 86% of 1004 randomly sampled Canadians read at least one book in the past year, compared to 81% of 1009 randomly sampled Britons. If we compare proportions of Britons and Canadians who read books, the 10% Condition is fulfilled.

A. True

B. False


Researchers conduct a study to test a potential side effect of a new allergy medication. A random sample of 160 subjects with allergies was selected for the study. The new “ improved” Brand I medication was randomly assigned to 80 subjects, and the current Brand C medication was randomly assigned to the other 80 subjects. 14 of the 80 patients with Brand I reported drowsiness, and 22 of the 80 patients with Brand C reported drowsiness.

We want of compute a 95% confidence interval for the difference in proportions of subjects reporting drowsiness, however we cannot since the samples are not independent.

A.True

B. False


Researchers conduct a study to test a potential side effect of a new allergy medication. A random sample of 160 subjects with allergies was selected for the study. The new “ improved” Brand I medication was randomly assigned to 80 subjects, and the current Brand C medication was randomly assigned to the other 80 subjects. 14 of the 80 patients with Brand I reported drowsiness, and 22 of the 80 patients with Brand C reported drowsiness.

We want of compute a 95% confidence interval for the difference in proportions of subjects reporting drowsiness, however we cannot since the samples are not independent.

A.True

B. False


When testing the difference between two proportions, we need to check the Success/Failure Condition. Which of the following is true?

I. If only the smaller sample passes the Success/Failure Condition, we can proceed with the test.

II. If only the larger sample passes the Success/Failure Condition, we can proceed with the test.

III. Both samples must pass the Success/Failure Condition to proceed with the test.

A. I only

B. II only

C. III only

D. None of the above.


When testing the difference between two proportions, we need to check the Success/Failure Condition. Which of the following is true?

I. If only the smaller sample passes the Success/Failure Condition, we can proceed with the test.

II. If only the larger sample passes the Success/Failure Condition, we can proceed with the test.

III. Both samples must pass the Success/Failure Condition to proceed with the test.

A. I only

B. II only

C. III only



A relief fund is set up to collect donations for the families affected by recent storms. A random sample of 400 people shows that 28% of those 200 who were contacted by telephone actually made contributions compared to only 18% of the 200 who received first class mail requests. Which formula calculates the 95% confidence interval for the difference in the proportions of people who make donations if contacted by telephone or first class mail?

A.

B.

C.

D.

(0.28 - 0.18) ±1.96

(0.23)(0.77)

200

(0.28 - 0.18) ±1.96

(0.23)(0.77)

400

(0.28 - 0.18) ±1.96

(0.23)(0.77)

200

(0.23)(0.77)

200

(0.28)(0.72) (0.18)(0.82)

(0.28 - 0.18) ±1.96200 200


A relief fund is set up to collect donations for the families affected by recent storms. A random sample of 400 people shows that 28% of those 200 who were contacted by telephone actually made contributions compared to only 18% of the 200 who received first class mail requests. Which formula calculates the 95% confidence interval for the difference in the proportions of people who make donations if contacted by telephone or first class mail?

A.

B.

C.

D.

(0.28 - 0.18) ±1.96

(0.23)(0.77)

200

(0.28 - 0.18) ±1.96

(0.23)(0.77)

400

(0.28 - 0.18) ±1.96

(0.23)(0.77)

200

(0.23)(0.77)

200

(0.28)(0.72) (0.18)(0.82)

(0.28 - 0.18) ±1.96200 200


A college alumni fund appeals for donations by phoning or emailing recent graduates. A random sample of 300 alumni shows that 40% of the 150 who were contacted by telephone actually made contributions compared to only 30% of the 150 who received email requests. Which formula calculates the 98% confidence interval for the difference in the proportions of alumni who may make donations if contacted by phone or by email?

A.

B.

C.

D.

(0.35)(0.65)(0.40 - 0.30) ± 2.33

150

(0.35)(0.65)(0.40 - 0.30) ± 2.33

300

(0.35)(0.65) (0.35)(0.65)

(0.40 - 0.30) ± 2.33150 150

(0.40)(0.60) (0.30)(0.70)

(0.40 - 0.30) ± 2.33150 150


A college alumni fund appeals for donations by phoning or emailing recent graduates. A random sample of 300 alumni shows that 40% of the 150 who were contacted by telephone actually made contributions compared to only 30% of the 150 who received email requests. Which formula calculates the 98% confidence interval for the difference in the proportions of alumni who may make donations if contacted by phone or by email?

A.

B.

C.

D.

(0.35)(0.65)(0.40 - 0.30) ± 2.33

150

(0.35)(0.65)(0.40 - 0.30) ± 2.33

300

(0.35)(0.65) (0.35)(0.65)

(0.40 - 0.30) ± 2.33150 150

(0.40)(0.60) (0.30)(0.70)

(0.40 - 0.30) ± 2.33150 150


A June 2004 public opinion poll asked 1000 randomly selected adults whether the United States should decrease the amount of immigration allowed; 49% of those responding said “yes.” In June 1995, a random sample of 1000 had found that 65% of adults thought immigration should be curtailed.

For opinion polls like this, which has more variability, the percentage of respondents answering “yes” or the difference in percentages between the two years.

A. The percentage of respondents answering “yes” in either year.

B. The difference in percentages between the two years.


A June 2004 public opinion poll asked 1000 randomly selected adults whether the United States should decrease the amount of immigration allowed; 49% of those responding said “yes.” In June 1995, a random sample of 1000 had found that 65% of adults thought immigration should be curtailed.

For opinion polls like this, which has more variability, the percentage of respondents answering “yes” or the difference in percentages between the two years.

A. The percentage of respondents answering “yes” in either year.

B. The difference in percentages between the two years.





Chapter 23: Inferences About Means


Which of the following is not an assumption or condition that needs to be checked for a one-sample t-test done on a sample drawn without replacement?

A. Randomization

B. 10% Condition

C. Success/Failure Condition

D. Nearly Normal Condition


Which of the following is not an assumption or condition that needs to be checked for a one-sample t-test done on a sample drawn without replacement?

A. Randomization

B. 10% Condition




Which statement correctly compares t-distributions to the normal distribution?

I. t distributions are also mound shaped and symmetric.

II. t distributions have less spread than the normal distribution.

III. As degrees of freedom increase, the variance of t-distributions becomes smaller.

A. I only

B. II only

C. I and II only

D. I and III only


Which statement correctly compares t-distributions to the normal distribution?

I. t distributions are also mound shaped and symmetric.

II. t distributions have less spread than the normal distribution.

III. As degrees of freedom increase, the variance of t-distributions becomes smaller.

A. I only

B. II only

C. I and II only

D. I and III only


Which of the following is true aboutStudent’s t-models?

A. They are unimodal, symmetric, and bell shaped.

B. They have fatter tails than the Normal model.

C. As the degrees of freedom increase, the t-models look more and more like the Normal Model

D. All of the above.


Which of the following is true aboutStudent’s t-models?

A. They are unimodal, symmetric, and bell shaped.

B. They have fatter tails than the Normal model.

C. As the degrees of freedom increase, the t-models look more and more like the Normal Model

D. All of the above.


A random sample of 120 classrooms at a large university found that 70% of them had been cleaned properly. What is the standard error of the sample proportion?

A. 0.028

B. 0.042

C. 0.046

D. 0.458


A random sample of 120 classrooms at a large university found that 70% of them had been cleaned properly. What is the standard error of the sample proportion?

A. 0.028

B. 0.042

C. 0.046

D. 0.458


A researcher found that a 98% confidence intervalfor the mean hours per week spent studying bycollege students was (13, 17). Which is true?

A. There is a 98% chance that the mean hours per week spent studying by college students is between 13 and 17 hours.

B. We are 98% sure that the mean hours per week spent studying by college students is between 13 and 17 hours.

C. Students average between 13 and 17 hours per week studying on 98% of the weeks.

D. 98% of all students spend between 13 and 17 hours studying per week.


A researcher found that a 98% confidence intervalfor the mean hours per week spent studying bycollege students was (13, 17). Which is true?

A. There is a 98% chance that the mean hours per week spent studying by college students is between 13 and 17 hours.

B. We are 98% sure that the mean hours per week spent studying by college students is between 13 and 17 hours.

C. Students average between 13 and 17 hours per week studying on 98% of the weeks.

D. 98% of all students spend between 13 and 17 hours studying per week.


A professor was curious about her students’ grade point averages (GPAs). She took a random sample of 15 students and found a mean GPA of 3.01 with a standard deviation of 0.534. Which of the following formulas gives a 99% confidence interval for the mean GPA of the professor’s students?

•

•

•

•

0.5343.01± 2.947

15

0.5343.01± 2.977

15

0.5343.01± 2.947

14

0.5343.01± 2.576

15


A professor was curious about her students’ grade point averages (GPAs). She took a random sample of 15 students and found a mean GPA of 3.01 with a standard deviation of 0.534. Which of the following formulas gives a 99% confidence interval for the mean GPA of the professor’s students?

•

•

•

•

0.5343.01± 2.947

15

0.5343.01± 2.977

15

0.5343.01± 2.947

14

0.5343.01± 2.576

15


A coffee house owner knows that customers pour different amounts of coffee into their cups. She samples cups from 10 costumers she believes to be representative of the customers and weighs the cups, finding a mean of 12.5 ounces and standard deviation of 0.5 ounces. Assuming these cups of coffee can be considered a random sample of all cups of coffee which of the following formulas gives a 95% confidence interval for the mean weight of all cups of coffee?

A.

B.

C.

D.

12.5 ± 2.228

0.5

10

0.512.5 ±1.96

10

0.512.5 ± 2.262

10

0.512.5 ± 2.262

9


A coffee house owner knows that customers pour different amounts of coffee into their cups. She samples cups from 10 costumers she believes to be representative of the customers and weighs the cups, finding a mean of 12.5 ounces and standard deviation of 0.5 ounces. Assuming these cups of coffee can be considered a random sample of all cups of coffee which of the following formulas gives a 95% confidence interval for the mean weight of all cups of coffee?

A.

B.

C.

D.

12.5 ± 2.228

0.5

10

0.512.5 ±1.96

10

0.512.5 ± 2.262

10

0.512.5 ± 2.262

9


A wildlife biologist wants to determine the mean weight of adult red squirrels. She captures 10 squirrels she believes to be representative of the species and weighs them, finding a mean of 12.32 grams and standard deviation of 1.88gm. Assuming these squirrels can be considered a random sample of all red squirrels which of the following formulas gives a 95% confidence interval for the mean weight of all squirrels?

A.

B.

C.

D.

1.8812.32 ±1.96

10

1.8812.32 ± 2.228

10

1.8812.32 ± 2.262

10

1.8812.32 ± 2.268

9


A wildlife biologist wants to determine the mean weight of adult red squirrels. She captures 10 squirrels she believes to be representative of the species and weighs them, finding a mean of 12.32 grams and standard deviation of 1.88gm. Assuming these squirrels can be considered a random sample of all red squirrels which of the following formulas gives a 95% confidence interval for the mean weight of all squirrels?

A.

B.

C.

D.

1.8812.32 ±1.96

10

1.8812.32 ± 2.228

10

1.8812.32 ± 2.262

10

1.8812.32 ± 2.268

9





Chapter 24: Comparing Means


A philosophy professor wants to find out whether the mean age of the men in his large lecture class is equal to the mean age of the women in his class. After collecting data from his students, the professor tested the hypothesis against the alternative . The P-value for the test was 0.003. Which is true?

H0:

M-

W= 0

A. There is a 0.3% chance that the mean age for the men is equal to the mean age for the women.

B. There is a 0.3% chance that the mean age for the men is different from the mean age of the women.

C. It is very unlikely that the professor would see results like these if the mean age of men was equal to the mean age of women.

D. There is a 0.3% chance that another sample will give these same results.

HA:

M-

W 0


A philosophy professor wants to find out whether the mean age of the men in his large lecture class is equal to the mean age of the women in his class. After collecting data from his students, the professor tested the hypothesis against the alternative . The P-value for the test was 0.003. Which is true?

A. There is a 0.3% chance that the mean age for the men is equal to the mean age for the women.

B. There is a 0.3% chance that the mean age for the men is different from the mean age of the women.

C. It is very unlikely that the professor would see results like these if the mean age of men was equal to the mean age of women.

D. There is a 0.3% chance that another sample will give these same results.

H0:

M-

W= 0

HA:

M-

W 0


Absorption rates into the body are important considerations when manufacturing a generic version of a brand-name drug. A pharmacist read that the absorption rate into the body of a new generic drug (G) is the same as its brand-name counterpart (B).She has a researcher friend of hers run a small experiment to test against the alternative . Which of the following would be a Type I error?

A. Deciding that the absorption rates are different, when in fact they are not.

B. Deciding that the absorption rates are different, when in fact they are.

C. Deciding that the absorption rates are the same, when in fact they are not.

D. Deciding that the absorption rates are the same, when in fact they are.

H0:

G-

B= 0 HA

: G

- B

0


Absorption rates into the body are important considerations when manufacturing a generic version of a brand-name drug. A pharmacist read that the absorption rate into the body of a new generic drug (G) is the same as its brand-name counterpart (B).She has a researcher friend of hers run a small experiment to test against the alternative . Which of the following would be a Type I error?

A. Deciding that the absorption rates are different, when in fact they are not.

B. Deciding that the absorption rates are different, when in fact they are.

C. Deciding that the absorption rates are the same, when in fact they are not.

D. Deciding that the absorption rates are the same, when in fact they are.

H0:

G-

B= 0 HA

: G

- B

0


Doctors at a technology research facility randomly assigned equal numbers of people to use computer keyboards in two rooms. In one room a group of people typed a manuscript using standard keyboards, while in the other room people typed the same manuscript using ergonomic keyboards to see if those people could type more words per minute. After collecting data for several days the researchers tested the hypothesis against the one-tail alternative and found a P-value of 0.22. Which is true?

A) The people using ergonomic keyboards type 22% more words per minute.

B) There’s a 22% chance that people using ergonomic keyboards type more words per minute.

C) There’s a 22% chance that there’s really no difference in typing speed.

D) There’s a 22% chance another experiment will give these same results.

E) None of these.

H0:

1-

2= 0


Doctors at a technology research facility randomly assigned equal numbers of people to use computer keyboards in two rooms. In one room a group of people typed a manuscript using standard keyboards, while in the other room people typed the same manuscript using ergonomic keyboards to see if those people could type more words per minute. After collecting data for several days the researchers tested the hypothesis against the one-tail alternative and found a P-value of 0.22. Which is true?

A) The people using ergonomic keyboards type 22% more words per minute.

B) There’s a 22% chance that people using ergonomic keyboards type more words per minute.

C) There’s a 22% chance that there’s really no difference in typing speed.

D) There’s a 22% chance another experiment will give these same results.

E) None of these.

H0:

1-

2= 0


Which of the following is not an assumption or condition that needs to be checked for a two-sample t-test for the difference between two means?

A. Independent Groups

B. Randomization

C. 10% Condition


E. All of the above must be checked.


Which of the following is not an assumption or condition that needs to be checked for a two-sample t-test for the difference between two means?

A. Independent Groups

B. Randomization

C. 10% Condition


E. All of the above must be checked.


Trainers need to estimate the level of fat in athletes to ensure good health. Initial tests were based on a small sample but now the trainers double the sample size for a follow-up test. The main purpose of the larger sample is to…

A. reduce response bias.

B. reduce non-response bias.

C. decrease the variability in the population.

D. reduce confounding due to other variables.

E. decrease the standard deviation of the samplingmodel.


Trainers need to estimate the level of fat in athletes to ensure good health. Initial tests were based on a small sample but now the trainers double the sample size for a follow-up test. The main purpose of the larger sample is to…

A. reduce response bias.

B. reduce non-response bias.

C. decrease the variability in the population.

D. reduce confounding due to other variables.

E. decrease the standard deviation of the samplingmodel.


Based on data from two very large independent samples, two students tested a hypothesis about equality of population means using α = 0.02. One student used a one-tail test and rejected the null hypothesis, but the other used a two-tail test and failed to reject the null. Which of these might have been their calculated value of t ?

A. 1.22

B. 1.55

C. 2.22

D. 1.88


Based on data from two very large independent samples, two students tested a hypothesis about equality of population means using α = 0.02. One student used a one-tail test and rejected the null hypothesis, but the other used a two-tail test and failed to reject the null. Which of these might have been their calculated value of t ?

A. 1.22

B. 1.55

C. 2.22

D. 1.88


A contact lens wearer read that the producer of a new contact lens boasts that their lenses are cheaper than contact lenses from another popular company. The null hypothesis is tested against the alternative . Which of the following would be a Type II error?

H0:

old-

new= 0

A. Deciding that the new lenses are cheaper, when in fact they really are.

B. Deciding that the new lenses are cheaper, when in fact they are not.

C. Deciding that the new lenses are not really cheaper, when in fact they are.

D. Deciding that the new lenses are not really cheaper, when in fact they are not.

HA:

old-

new> 0


A contact lens wearer read that the producer of a new contact lens boasts that their lenses are cheaper than contact lenses from another popular company. The null hypothesis is tested against the alternative . Which of the following would be a Type II error?

H0:

old-

new= 0

A. Deciding that the new lenses are cheaper, when in fact they really are.

B. Deciding that the new lenses are cheaper, when in fact they are not.

C. Deciding that the new lenses are not really cheaper, when in fact they are.

D. Deciding that the new lenses are not really cheaper, when in fact they are not.

HA:

old-

new> 0


There is never a time when assuming equal variances makes sense.

A. True

B. False


There is never a time when assuming equal variances makes sense.

A. True

B. False





Chapter 25: Paired Samples and Blocks


To construct a confidence interval for the mean ofpaired data, we

A. treat the data as if it is two independent samples and construct a two-sample t-interval.

B. find the differences between the data and construct a one-sample t-interval.

C. find the proportion of the data pairs with increases and construct a one-proportion z-interval.

D. cannot do anything to construct a confidence interval.


To construct a confidence interval for the mean ofpaired data, we

A. treat the data as if it is two independent samples and construct a two-sample t-interval.

B. find the differences between the data and construct a one-sample t-interval.

C. find the proportion of the data pairs with increases and construct a one-proportion z-interval.

D. cannot do anything to construct a confidence interval.


Which of the following is not an assumption or condition that needs to be checked fora paired t-interval?

A. Paired Data

B. Independent Groups

C. Randomization

D. 10% Condition

E. Nearly Normal Condition


Which of the following is not an assumption or condition that needs to be checked fora paired t-interval?

A. Paired Data

B. Independent Groups

C. Randomization

D. 10% Condition

E. Nearly Normal Condition


Do twins score the same on IQ tests? The following table shows IQ scores for a random sample of twins:

We want to conduct the appropriate hypothesis test to test if twins score the same on IQ tests. If d = Twin A IQ – Twin B IQ, and then,

A.

B.

C.

Twin A 84 106 113 112 97 115 121Twin B 77 104 106 113 102 103 117

H0:

d= 0

HA:

d0

HA:

d< 0

HA:

d> 0


Do twins score the same on IQ tests? The following table shows IQ scores for a random sample of twins:

We want to conduct the appropriate hypothesis test to test if twins score the same on IQ tests. If d = Twin A IQ – Twin B IQ, and then,

A.

B.

C.

Twin A 84 106 113 112 97 115 121Twin B 77 104 106 113 102 103 117

H0:

d= 0

HA:

d0

HA:

d< 0

HA:

d> 0


Before you took this course, you probably heard many stories about intro stats courses. Oftentimes parents of students have had bad experiences with intro stats courses and pass on their anxieties to their children. To test whether actually taking intro stats decreases students’ anxieties about statistics, a statistics instructor gave a test to rate student anxiety at the beginning and end of his course. Anxiety levels were measured on a scale of 0-10. We decide to choose 20 students randomly from a class of 180 students. If we proceed in this manner, which condition is violated:

A. Independence

B. Randomization

C. 10% Condition



Before you took this course, you probably heard many stories about intro stats courses. Oftentimes parents of students have had bad experiences with intro stats courses and pass on their anxieties to their children. To test whether actually taking intro stats decreases students’ anxieties about statistics, a statistics instructor gave a test to rate student anxiety at the beginning and end of his course. Anxiety levels were measured on a scale of 0-10. We decide to choose 20 students randomly from a class of 180 students. If we proceed in this manner, which condition is violated:

A. Independence

B. Randomization

C. 10% Condition



A paired design is an example of

A. Blinding

B. Blocking

C. Confounding

D. Matching


A paired design is an example of

A. Blinding

B. Blocking

C. Confounding

D. Matching


Random samples of 50 men and 50 women are asked to imagine buying a birthday present for their best friend. We want to estimate the difference in how much they are willing to spend. We would use a

A. Two-sample t hypothesis test.

B. Two-sample t confidence interval.

C. Paired t hypothesis test.

D. Paired t confidence interval.


Random samples of 50 men and 50 women are asked to imagine buying a birthday present for their best friend. We want to estimate the difference in how much they are willing to spend. We would use a






Are parents equally strict with boys and girls? In a random sample of families, researchers asked a brother and sister from each family to rate how strict their parents were. We would use a






Are parents equally strict with boys and girls? In a random sample of families, researchers asked a brother and sister from each family to rate how strict their parents were. We would use a









Chapter 26: Comparing Counts


Which of the following is not an assumption or condition that needs to be checked for chi-square tests?

A. Counted Data

B. Randomization


D. Expected Cell Frequency


Which of the following is not an assumption or condition that needs to be checked for chi-square tests?

A. Counted Data

B. Randomization


D. Expected Cell Frequency


Which of the following is not true about chi-squaremodels?

A. They are unimodal and right skewed.

B. They can only take on nonnegative values.

C. They have degrees of freedom like t-models, although the degrees of freedom are calculated differently.

D. As the degrees of freedom increase, the chi-square models look more and more like the Normal.


Which of the following is not true about chi-squaremodels?

A. They are unimodal and right skewed.

B. They can only take on nonnegative values.

C. They have degrees of freedom like t-models, although the degrees of freedom are calculated differently.

D. As the degrees of freedom increase, the chi-square models look more and more like the Normal.


How many degrees of freedom are there for a chi-square test of independence with five rows and six columns?

A. 4

B. 5

C. 20

D. 24

E. 30


How many degrees of freedom are there for a chi-square test of independence with five rows and six columns?

A. 4

B. 5

C. 20

D. 24

E. 30


A test comparing the distribution of counts for two or more groups on the same categorical variable is called a test of

A. Independence

B. Homogeneity

C. Randomization

D. Normalization


A test comparing the distribution of counts for two or more groups on the same categorical variable is called a test of

A. Independence

B. Homogeneity

C. Randomization

D. Normalization


Whenever we reject the null hypothesis when conducting a test for homogeneity, it is a good idea to

A. change the sample size.

B. change the degrees of freedom.

C. examine the residuals.

D. leave the answer as is.


Whenever we reject the null hypothesis when conducting a test for homogeneity, it is a good idea to

A. change the sample size.

B. change the degrees of freedom.

C. examine the residuals.

D. leave the answer as is.


The degrees of freedom for chi-square tests grow with the sample size.

A. True

B. False


The degrees of freedom for chi-square tests grow with the sample size.

A. True

B. False


Goodness of fit tests compare

A. the observed distribution of a single categorical variable to an expected distribution based on a theory or model.

B. the distribution of several groups for the same categorical variable.

C. counts from a single group for evidence of an association between two categorical variables.



Goodness of fit tests compare

A. the observed distribution of a single categorical variable to an expected distribution based on a theory or model.

B. the distribution of several groups for the same categorical variable.

C. counts from a single group for evidence of an association between two categorical variables.



Could eye color be a warning signal for hearing loss in patients suffering from meningitis? British researcher Helen Cullington recorded the eye color of 130 deaf patients, and noted whether the patient’s deafness had developed following treatmentfor meningitis. Her data are summarized in the table below. After setting up the appropriate hypothesis, what is the P-value?

A. 0.15

B. 0.015

C. 0.0015

D. 1.5

Eye Color Meningitis 0therLight 30 72Dark 2 26

Deafness related to …


Could eye color be a warning signal for hearing loss in patients suffering from meningitis? British researcher Helen Cullington recorded the eye color of 130 deaf patients, and noted whether the patient’s deafness had developed following treatmentfor meningitis. Her data are summarized in the table below. After setting up the appropriate hypothesis, what is the P-value?

A. 0.15

B. 0.015

C. 0.0015

D. 1.5

Eye Color Meningitis 0therLight 30 72Dark 2 26

Deafness related to …

Documents

Slide 20 - 1 Copyright © 2009 Pearson Education, Inc. Active Learning Lecture Slides For use with Classroom Response Systems Intro Stats Third Edition