Question 1

The large-sample confidence interval for p1 - p2 generally has a true confidence level ___________the level asked for.

Accepted Answer

A) greater than 
B) less than 
C) equal to 
A) greater than 
B) less than 
C) equal to

Question 2

Avandia is an antidiabetic drug and, like all drugs, it can have side effects. One study of patients with congestive heart failure found that 5 of the 110 subjects randomly assigned to take Avandia died of a cardiovascular event during the duration of the study, compared with 4 of the 114 subjects assigned to the placebo. The research question is "Is there evidence that patients with congestive heart failure have a higher probability of dying of a cardiovascular event if they take Avandia than if they take a placebo?" Using technology, what is the P-value of this test?

Accepted Answer

A) Greater than 0.10 
B) Between 0.05 and 0.10 
C) Between 0.01 and 0.05 
D) Less than 0.01 
A) Greater than 0.10 
B) Between 0.05 and 0.10 
C) Between 0.01 and 0.05 
D) Less than 0.01

Question 3

We cannot draw a conclusion about causation from an observational study even if the P-value is statistically significant because of confounding variables.

Accepted Answer

A) True 
 B)False

Question 4

Avandia is an antidiabetic drug and, like all drugs, it can have side effects. One study of patients with congestive heart failure found that 5 of the 110 subjects randomly assigned to take Avandia died of a cardiovascular event during the duration of the study, compared with 4 of the 114 subjects assigned to the placebo. The research question is "Is there evidence that patients with congestive heart failure have a higher probability of dying of a cardiovascular event if they take Avandia than if they take a placebo?" What is the relative risk of cardiovascular death when taking Avandia compared with taking a placebo?

Accepted Answer

A) 1.30 
B) 1.25 
C) 0.77 
D) 0.23 
A) 1.30 
B) 1.25 
C) 0.77 
D) 0.23

Question 5

Could cancer cells be selectively targeted by using antibodies recognizing a tumor-specific protein marker? Researchers grafted human cancerous cells onto 20 healthy adult mice and then randomly assigned 10 of these mice to be treated with tumor-specific antibodies. They found that only 1 of the 10 mice treated with antibodies developed metastases (i.e., new cancer growths), whereas all 10 of the 10 mice in the control group developed metastases. What is the plus four estimate for the proportion of mice developing metastases in the treatment group?

Accepted Answer

A) 0.1000 
B) 0.1667 
C) 0.2143 
D) 0.5000 
A) 0.1000 
B) 0.1667 
C) 0.2143 
D) 0.5000

Question 6

Avandia is an antidiabetic drug and, like all drugs, it can have side effects. One study of patients with congestive heart failure found that 5 of the 110 subjects randomly assigned to take Avandia died of a cardiovascular event during the duration of the study, compared with 4 of the 114 subjects assigned to the placebo. The research question is "Is there evidence that patients with congestive heart failure have a higher probability of dying of a cardiovascular event if they take Avandia than if they take a placebo?" Using technology, what is the test statistic for this hypothesis test?

Accepted Answer

A) 0.395 
B) 1.354 
C) 2.055 
D) 2.851 
A) 0.395 
B) 1.354 
C) 2.055 
D) 2.851

Question 7

A random digit dialing sample of 1750 adults found that 1140 used some form of prescription medication. Of those who used prescription drugs, 940 said they are concerned about the current state of health care; 320 of the 610 nonusers agreed with this position as well. What is the estimate for the proportion of adults who use prescription drugs and who are concerned?

Accepted Answer

A) 0.183 
B) 0.525 
C) 0.537 
D) 0.825 
A) 0.183 
B) 0.525 
C) 0.537 
D) 0.825

Question 8

Is there a difference in the proportion of individuals with food allergies between young children and adults? We plan to test the following hypotheses:
​
H0:pChildren = pAdults, H0:pChildren ≠ pAdults
A survey finds that 13 among a simple random sample of 184 young children have some food allergy, compared with 4 out of 163 adults. Using technology, what is the test statistic for this hypothesis test?

Accepted Answer

A) 0.046 
B) 1.986 
C) 2.055 
D) 2.851 
A) 0.046 
B) 1.986 
C) 2.055 
D) 2.851

Question 9

A phytologist is worried that a large proportion of the algae found in nearby water sources is cyanobacteria. In particular, he obtains a simple random sample of 50 algae from a local river and an independent simple random sample of 75 algae from the local coastline. He finds that 22 algae in the river sample and 66 algae in the coastline sample are cyanobacteria. He considers the river to act as a control group. Let p1 and p2 represent the proportion of cyanobacteria in riparian (i.e., river) and coastal populations, respectively. What is the absolute risk reduction from coastal to riparian environments of algae being cyanobacteria?

Accepted Answer

A) -0.4400 
B) -0.1071 
C) 0.4400 
D) 0.1071 
A) -0.4400 
B) -0.1071 
C) 0.4400 
D) 0.1071

Question 10

Avandia is an antidiabetic drug and, like all drugs, it can have side effects. One study of patients with congestive heart failure found that 5 of the 110 subjects randomly assigned to take Avandia died of a cardiovascular event during the duration of the study, compared with 4 of the 114 subjects assigned to the placebo. The research question is "Is there evidence that patients with congestive heart failure have a higher probability of dying of a cardiovascular event if they take Avandia than if they take a placebo?" What is the pooled proportion of subjects who died of a cardiovascular event during the study?

Accepted Answer

A) 0.0402 
B) 0.0450 
C) 0.0482 
D) 0.0500 
A) 0.0402 
B) 0.0450 
C) 0.0482 
D) 0.0500

Question 11

Could cancer cells be selectively targeted by using antibodies recognizing a tumor-specific protein marker? Researchers grafted human cancerous cells onto 20 healthy adult mice and then randomly assigned 10 of these mice to be treated with tumor-specific antibodies. They found that only 1 of the 10 mice treated with antibodies developed metastases (i.e., new cancer growth), whereas all 10 of the 10 mice in the control group developed metastases. We want to compare the proportions of mice developing metastases under the two conditions. Which of the following statements is correct regarding this hypothesis test?

Accepted Answer

A) The test is not appropriate because the respective counts of successes and failures are not large enough. 
B) The test is not appropriate because the experiment is not double-blind. 
C) The test is appropriate because a total of 20 mice is large enough for any inference. 
D) The test is appropriate because the study was randomized. 
A) The test is not appropriate because the respective counts of successes and failures are not large enough. 
B) The test is not appropriate because the experiment is not double-blind. 
C) The test is appropriate because a total of 20 mice is large enough for any inference. 
D) The test is appropriate because the study was randomized.

Question 12

A random digit dialing sample of 1750 adults found that 1140 used some form of prescription medication. Of those who used prescription drugs, 940 said they are concerned about the current state of health care; 320 of the 610 nonusers agreed with this position as well. Consider prescription drug users to be the reference group. What is the absolute risk reduction?

Accepted Answer

A) -0.3638 
B) -0.3000 
C) 0.3000 
D) 0.3638 
A) -0.3638 
B) -0.3000 
C) 0.3000 
D) 0.3638

Question 13

A random digit dialing sample of 1750 adults found that 1140 used some form of prescription medication. Of those who used prescription drugs, 940 said they are concerned about the current state of health care; 320 of the 610 nonusers agreed with this position as well. Consider prescription drug users to be the reference group. What is the odds ratio of being concerned?

Accepted Answer

A) 0.2348 
B) 1.1034 
C) 4.2594 
D) 4.7000 
A) 0.2348 
B) 1.1034 
C) 4.2594 
D) 4.7000

Question 14

A pioneer study randomly assigned pregnant women to either a daily multivitamin supplement (including folic acid) or a placebo. In the 2104 pregnancies in the women taking the vitamin regimen, there were 28 cases of congenital malformation. In the 2052 pregnancies in the women taking the placebo, 47 cases of congenital malformation were recorded. Rounded to the nearest whole number, what is the number needed to treat, NNT, to prevent one congenital malformation when taking a multivitamin supplement compared with taking a placebo?

Accepted Answer

A) 1053 
B) 104 
C) 100 
D) 58 
A) 1053 
B) 104 
C) 100 
D) 58

Question 15

Is there a difference in the proportion of individuals with food allergies between young children and adults? We plan to test the following hypotheses:
​
H0:pChildren = pAdults, H0:pChildren ≠ pAdults
A survey finds that 13 among a simple random sample of 184 young children have some food allergy, compared with 4 out of 163 adults. Using technology, what is the P-value of this test?

Accepted Answer

A) Greater than 0.10 
B) Between 0.05 and 0.10 
C) Between 0.01 and 0.05 
D) Less than 0.01 
A) Greater than 0.10 
B) Between 0.05 and 0.10 
C) Between 0.01 and 0.05 
D) Less than 0.01

Question 16

A study recorded the body mass index (BMI) of a simple random sample of 200 American men and 200 American women. Individuals with a BMI greater than 30 are considered obese. To estimate the difference in the percentage of individuals who are obese among American men and American women, which inference procedure should you use?

Accepted Answer

A) One-sample z procedure for a proportion 
B) Two-sample z procedure for proportions 
C) One-sample or matched pairs z or t procedure for a mean 
D) Two-sample z or t procedure for means 
A) One-sample z procedure for a proportion 
B) Two-sample z procedure for proportions 
C) One-sample or matched pairs z or t procedure for a mean 
D) Two-sample z or t procedure for means

Question 17

The Virginia Department of Environmental Quality (VDEQ) uses probabilistic monitoring to regulate the water quality of streams in the Commonwealth of Virginia. Of the 85 Eastern Virginia Sites (group 1), 17 do not meet minimum requirements. Of the 80 units sampled in Western Virginia Sites (group 2), 24 do not meet minimum requirements. Assume the data can be treated as independent simple random samples. What are the null and alternative hypotheses to test that the proportions of streams that fail to meet minimum requirements in the two areas are equal?

Accepted Answer

A)  $H _ { 0 } : p _ { 1 } = p _ { 2 } , H _ { a } : p _ { 1 }  p _ { 2 }$ 
C)  $H _ { 0 } : p _ { 1 } = p _ { 2 } , H _ { a } : p _ { 1 } \neq p _ { 2 }$ 
D)  $H _ { 0 } : p _ { 1 } \neq p _ { 2 } , H _ { a } : p _ { 1 } = p _ { 2 }$ 
A)  $H _ { 0 } : p _ { 1 } = p _ { 2 } , H _ { a } : p _ { 1 }  p _ { 2 }$ 
C)  $H _ { 0 } : p _ { 1 } = p _ { 2 } , H _ { a } : p _ { 1 } \neq p _ { 2 }$ 
D)  $H _ { 0 } : p _ { 1 } \neq p _ { 2 } , H _ { a } : p _ { 1 } = p _ { 2 }$

Question 18

Could cancer cells be selectively targeted by using antibodies recognizing a tumor-specific protein marker? Researchers grafted human cancerous cells onto 20 healthy adult mice and then randomly assigned 10 of these mice to be treated with tumor-specific antibodies. They found that only 1 of the 10 mice treated with antibodies developed metastases (i.e., new cancer growths), whereas all 10 of the 10 mice in the control group developed metastases. What is the plus four estimate for the proportion of mice developing metastases in the control group?

Accepted Answer

A) 0.5000 
B) 0.8571 
C) 0.9167 
D) 1.0000 
A) 0.5000 
B) 0.8571 
C) 0.9167 
D) 1.0000

Question 19

A random digit dialing sample of 1750 adults found that 1140 used some form of prescription medication. Of those who used prescription drugs, 940 said they are concerned about the current state of health care; 320 of the 610 nonusers agreed with this position as well. Consider prescription drug users to be the reference group. What is the relative risk reduction?

Accepted Answer

A) -0.5718 
B) -0.3638 
C) 0.3638 
D) 0.5718 
A) -0.5718 
B) -0.3638 
C) 0.3638 
D) 0.5718

Question 20

A phytologist is worried that a large proportion of the algae found in nearby water sources is cyanobacteria. In particular, he obtains a simple random sample of 50 algae from a local river and an independent simple random sample of 75 algae from the local coastline. He finds that 22 algae in the river sample and 66 algae in the coastline sample are cyanobacteria. He considers the river to act as a control group. Let p1 and p2 represent the proportion of cyanobacteria in riparian (i.e., river) and coastal populations, respectively. Using technology, what is a 99% confidence interval for p1-p2?

Accepted Answer

A) -0.44 ± 0.0163 
B) -0.44 ± 0.1896 
C) -0.44 ± 0.2054 
D) -0.44 ± 0.2149 
A) -0.44 ± 0.0163 
B) -0.44 ± 0.1896 
C) -0.44 ± 0.2054 
D) -0.44 ± 0.2149

The large-sample confidence interval for p₁ - p₂ generally has a true confidence level ___________the level asked for.

We cannot draw a conclusion about causation from an observational study even if the P-value is statistically significant because of confounding variables.

Picturing Distributions With Graphs

Describing Quantitative Distributions With Numbers

Scatterplots and Correlation

Regression

Two-Way Tables

Samples and Observational Studies

Designing Experiments

Essential Probability Rules

Independence and Conditional Probabilities

The Normal Distributions

Discrete Probability Distributions

Sampling Distributions

Introduction to Inference

Exercises

Inference About a Population Mean

Comparing Two Means

Inference About a Population Proportion

The Chi-Square Test for Goodness of Fit

The Chi-Square Test for Two-Way Tables

Inference for Regression

One-Way Analysis of Variance: Comparing Several Means

More About Analysis of Variance: Follow-Up Tests and Two-Way Anova

Nonparametric Tests

Multiple and Logistic Regression

Filters

Exam 18: Comparing Two Proportions

The large-sample confidence interval for p1 - p2 generally has a true confidence level ___________the level asked for.

We cannot draw a conclusion about causation from an observational study even if the P-value is statistically significant because of confounding variables.

Picturing Distributions With Graphs

Describing Quantitative Distributions With Numbers

Scatterplots and Correlation

Regression

Two-Way Tables

Samples and Observational Studies

Designing Experiments

Essential Probability Rules

Independence and Conditional Probabilities

The Normal Distributions

Discrete Probability Distributions

Sampling Distributions

Introduction to Inference

Exercises

Inference About a Population Mean

Comparing Two Means

Inference About a Population Proportion

The Chi-Square Test for Goodness of Fit

The Chi-Square Test for Two-Way Tables

Inference for Regression

One-Way Analysis of Variance: Comparing Several Means

More About Analysis of Variance: Follow-Up Tests and Two-Way Anova

Nonparametric Tests

Multiple and Logistic Regression

Filters

The large-sample confidence interval for p₁ - p₂ generally has a true confidence level ___________the level asked for.