Deck 9: Contingency Analysis: Associations Between

Question 1

Consider a study in which people were recruited and followed for 40 years to determine their health problems. The researchers were interested in lung cancer so at the end of the study they counted the number of participants who had died from lung cancer, or currently had it, and those that did not. They also counted how many were non-smokers their whole life or had been smokers at some point in their lives. The number of non-smokers with lung cancer was 36 and the number of non-smokers with no sign of lung cancer was 815. The number of smokers with lung cancer was 26 and the number of smokers with no sign of lung cancer was 161.
What proportion of all participants had been, or currently were, smokers?

A) 6%
B) 18%
C) 24%
D) 30%

Answer 1

B

Question 2

Consider a study in which people were recruited and followed for 40 years to determine their health problems. The researchers were interested in lung cancer so at the end of the study they counted the number of participants who had died from lung cancer, or currently had it, and those that did not. They also counted how many were non-smokers their whole life or had been smokers at some point in their lives. The number of non-smokers with lung cancer was 36 and the number of non-smokers with no sign of lung cancer was 815. The number of smokers with lung cancer was 26 and the number of smokers with no sign of lung cancer was 161.
What is the relative risk of lung cancer for participants who were smokers?

A) 3.29
B) 3.66
C) 4.02
D) 4.55

Answer 2

A

Question 3

Consider a study in which people were recruited and followed for 40 years to determine their health problems. The researchers were interested in lung cancer so at the end of the study they counted the number of participants who had died from lung cancer, or currently had it, and those that did not. They also counted how many were non-smokers their whole life or had been smokers at some point in their lives. The number of non-smokers with lung cancer was 36 and the number of non-smokers with no sign of lung cancer was 815. The number of smokers with lung cancer was 26 and the number of smokers with no sign of lung cancer was 161.
What is the odds ratio of lung cancer for participants who were smokers?

A) 3.29
B) 3.66
C) 4.02
D) 4.55

Answer 3

B

Question 4

Consider a study in which people were recruited and followed for 40 years to determine their health problems. The researchers were interested in lung cancer so at the end of the study they counted the number of participants who had died from lung cancer, or currently had it, and those that did not. They also counted how many were non-smokers their whole life or had been smokers at some point in their lives. The number of non-smokers with lung cancer was 36 and the number of non-smokers with no sign of lung cancer was 815. The number of smokers with lung cancer was 26 and the number of smokers with no sign of lung cancer was 161.
Assuming a null hypothesis of no relationship between smoking and risk of lung cancer, which of the following values is closest to the expected number of smokers who did not get lung cancer?

A) 131
B) 146
C) 161
D) 176

Question 5

Consider a study in which people were recruited and followed for 40 years to determine their health problems. The researchers were interested in lung cancer so at the end of the study they counted the number of participants who had died from lung cancer, or currently had it, and those that did not. They also counted how many were non-smokers their whole life or had been smokers at some point in their lives. The number of non-smokers with lung cancer was 36 and the number of non-smokers with no sign of lung cancer was 815. The number of smokers with lung cancer was 26 and the number of smokers with no sign of lung cancer was 161.
To determine whether there appears to be a significant relationship between smoking and risk of lung cancer we would conduct a χ² analysis. When performing this analysis, which of the values below is closest to the contribution to the χ² statistic from the "never smoked : had lung cancer"?

A) 0.97
B) 2.54
C) 4.33
D) 11.17

Question 6

Consider a study in which people were recruited and followed for 40 years to determine their health problems. The researchers were interested in lung cancer so at the end of the study they counted the number of participants who had died from lung cancer, or currently had it, and those that did not. They also counted how many were non-smokers their whole life or had been smokers at some point in their lives. The number of non-smokers with lung cancer was 36 and the number of non-smokers with no sign of lung cancer was 815. The number of smokers with lung cancer was 26 and the number of smokers with no sign of lung cancer was 161.
To determine whether there appears to be a statistically significant relationship between smoking and risk of lung cancer we would conduct a χ² analysis. When performing this analysis, which of the values below is closest to the χ² statistic we would obtain?

A) 21.54
B) 23.35
C) 25.54
D) 27.35

Question 7

Consider a study in which people were recruited and followed for 40 years to determine their health problems. The researchers were interested in lung cancer so at the end of the study they counted the number of participants who had died from lung cancer, or currently had it, and those that did not. They also counted how many were non-smokers their whole life or had been smokers at some point in their lives. The number of non-smokers with lung cancer was 36 and the number of non-smokers with no sign of lung cancer was 815. The number of smokers with lung cancer was 26 and the number of smokers with no sign of lung cancer was 161.
To determine whether there appears to be a statistically significant relationship between smoking and risk of lung cancer we would conduct a χ² analysis. Based on the results of this analysis, which of the following is the most appropriate conclusion?

A) Smoking appears to significantly elevate the risk of lung cancer (P > 0.05)
B) Smoking appears to significantly elevate the risk of lung cancer (P < 0.05)
C) Smoking appears to significantly reduce the risk of lung cancer (P < 0.01)
D) These data do not provide sufficient evidence that smoking changes the risk of lung cancer (P < 0.05)

Question 8

There are many claims that eating organic food leads to better health outcomes. To study this, a dietician collects data from her patients: she categorizes their blood pressure values into elevated and healthy and she administers a questionnaire from which she is able to classify their diet into high in organic food and low in organic food. The number of patients with high organic food consumption who had elevated and healthy blood pressures were 33 and 74 respectively. The number of patients with low organic food consumption who had elevated and healthy blood pressures were 267 and 395 respectively.
What proportion of all participants had elevated blood pressure?

A) 19%
B) 29%
C) 39%
D) 49%

Question 9

There are many claims that eating organic food leads to better health outcomes. To study this, a dietician collects data from her patients: she categorizes their blood pressure values into elevated and healthy and she administers a questionnaire from which she is able to classify their diet into high in organic food and low in organic food. The number of patients with high organic food consumption who had elevated and healthy blood pressures were 33 and 74 respectively. The number of patients with low organic food consumption who had elevated and healthy blood pressures were 267 and 395 respectively.
What is the relative risk of elevated blood pressure for participants with diets high in organic food?

A) 0.66
B) 0.76
C) 0.91
D) 1.52

Question 10

There are many claims that eating organic food leads to better health outcomes. To study this, a dietician collects data from her patients: she categorizes their blood pressure values into elevated and healthy and she administers a questionnaire from which she is able to classify their diet into high in organic food and low in organic food. The number of patients with high organic food consumption who had elevated and healthy blood pressures were 33 and 74 respectively. The number of patients with low organic food consumption who had elevated and healthy blood pressures were 267 and 395 respectively.
What is the odds ratio for elevated blood pressure for participants with diets high in organic food?

A) 0.66
B) 0.76
C) 0.91
D) 1.52

Question 11

There are many claims that eating organic food leads to better health outcomes. To study this, a dietician collects data from her patients: she categorizes their blood pressure values into elevated and healthy and she administers a questionnaire from which she is able to classify their diet into high in organic food and low in organic food. The number of patients with high organic food consumption who had elevated and healthy blood pressures were 33 and 74 respectively. The number of patients with low organic food consumption who had elevated and healthy blood pressures were 267 and 395 respectively.
Assuming a null hypothesis of no relationship between type of diet and blood pressure, which of the following values is closest to the expected number of patients who ate a diet low in organic food who would have elevated blood pressure?

A) 258
B) 294
C) 348
D) 404

Question 12

There are many claims that eating organic food leads to better health outcomes. To study this, a dietician collects data from her patients: she categorizes their blood pressure values into elevated and healthy and she administers a questionnaire from which she is able to classify their diet into high in organic food and low in organic food. The number of patients with high organic food consumption who had elevated and healthy blood pressures were 33 and 74 respectively. The number of patients with low organic food consumption who had elevated and healthy blood pressures were 267 and 395 respectively.
To determine whether there appears to be a statistically significant relationship between type of diet and blood pressure she would conduct a χ² analysis. When performing this analysis, which of the values below is closest to the contribution to the χ² statistic from the "high organic diet : elevated blood pressure" group?

A) 1.3
B) 1.8
C) 2.3
D) 2.8

Question 13

There are many claims that eating organic food leads to better health outcomes. To study this, a dietician collects data from her patients: she categorizes their blood pressure values into elevated and healthy and she administers a questionnaire from which she is able to classify their diet into high in organic food and low in organic food. The number of patients with high organic food consumption who had elevated and healthy blood pressures were 33 and 74 respectively. The number of patients with low organic food consumption who had elevated and healthy blood pressures were 267 and 395 respectively.
To determine whether there appears to be a statistically significant relationship between type of diet and blood pressure she would conduct a χ² analysis. When performing this analysis, which of the values below is closest to the χ² statistic she would obtain?

A) 2.51
B) 3.49
C) 5.23
D) 8.11

Question 14

There are many claims that eating organic food leads to better health outcomes. To study this, a dietician collects data from her patients: she categorizes their blood pressure values into elevated and healthy and she administers a questionnaire from which she is able to classify their diet into high in organic food and low in organic food. The number of patients with high organic food consumption who had elevated and healthy blood pressures were 33 and 74 respectively. The number of patients with low organic food consumption who had elevated and healthy blood pressures were 267 and 395 respectively.
To determine whether there appears to be a statistically significant relationship between type of diet and blood pressure she would conduct a χ² analysis. Based on the results of her analysis, which of the following is the most appropriate conclusion?

A) Eating higher amounts of organic food appears to significantly reduce the risk of high blood pressure (P > 0.05).
B) Eating higher amounts of organic food appears to significantly reduce the risk of high blood pressure (P < 0.05).
C) Eating higher amounts of organic food appears to significantly elevate the risk of high blood pressure (P < 0.05).
D) These data do not provide sufficient evidence that eating higher amounts of organic food changes the risk of high blood pressure (P > 0.05).

Question 15

Consider the following values for numbers of major traffic accidents involving male and female drivers. The accidents are divided into ones involving a fatality and ones that did not. What is the relative risk for male drivers with regard to fatal accidents?
$\begin{array}{|l|l|l|}\hline & \text { Males } & \text { Females } \\\hline \text { Fatal } & 275 & 142 \\\hline \text { Non-fatal } & 3024 & 564 \\\hline\end{array}$

-What proportion of all accidents involve one or more fatalities?

A) 10%
B) 13%
C) 19%
D) 43%

Question 16

Consider the following values for numbers of major traffic accidents involving male and female drivers. The accidents are divided into ones involving a fatality and ones that did not. What is the relative risk for male drivers with regard to fatal accidents?
$\begin{array}{|l|l|l|}\hline & \text { Males } & \text { Females } \\\hline \text { Fatal } & 275 & 142 \\\hline \text { Non-fatal } & 3024 & 564 \\\hline\end{array}$

-What is the relative risk of fatal accidents for males versus females?

A) 1.94
B) 2.41
C) 0.41
D) 0.36

Question 17

Consider the following values for numbers of major traffic accidents involving male and female drivers. The accidents are divided into ones involving a fatality and ones that did not. What is the relative risk for male drivers with regard to fatal accidents?
$\begin{array}{|l|l|l|}\hline & \text { Males } & \text { Females } \\\hline \text { Fatal } & 275 & 142 \\\hline \text { Non-fatal } & 3024 & 564 \\\hline\end{array}$

-What is the odds ratio of fatal accidents for males versus females?

A) 10.38
B) 2.77
C) 0.10
D) 0.36

Question 18

Consider the following values for numbers of major traffic accidents involving male and female drivers. The accidents are divided into ones involving a fatality and ones that did not. What is the relative risk for male drivers with regard to fatal accidents?
$\begin{array}{|l|l|l|}\hline & \text { Males } & \text { Females } \\\hline \text { Fatal } & 275 & 142 \\\hline \text { Non-fatal } & 3024 & 564 \\\hline\end{array}$

-Assuming a null hypothesis of no relationship between sex of the driver and fatality of their accidents, which of the following values is closest to the expected number of fatal accidents involving male drivers?

A) 73.5
B) 13.6
C) 343.5
D) 63.82

Question 19

Consider the following values for numbers of major traffic accidents involving male and female drivers. The accidents are divided into ones involving a fatality and ones that did not. What is the relative risk for male drivers with regard to fatal accidents?
$\begin{array}{|l|l|l|}\hline & \text { Males } & \text { Females } \\\hline \text { Fatal } & 275 & 142 \\\hline \text { Non-fatal } & 3024 & 564 \\\hline\end{array}$

-To determine whether there appears to be a statistically significant relationship between sex of the driver and fatality of their accidents we would conduct a ?² analysis. When performing this analysis, which of the values below is closest to the contribution to the ?² statistic from the "non-fatal : female" category?

A) 1.52
B) 7.42
C) 13.66
D) 63.82

Question 20

Consider the following values for numbers of major traffic accidents involving male and female drivers. The accidents are divided into ones involving a fatality and ones that did not. What is the relative risk for male drivers with regard to fatal accidents?
$\begin{array}{|l|l|l|}\hline & \text { Males } & \text { Females } \\\hline \text { Fatal } & 275 & 142 \\\hline \text { Non-fatal } & 3024 & 564 \\\hline\end{array}$

-To determine whether there appears to be a statistically significant relationship between sex of the driver and fatality of their accidents we would conduct a ?² analysis. When performing this analysis, which of the values below is closest to the ?² statistic we would obtain?

A) 86.5
B) 569.1
C) 60.0
D) 21.94

Question 21

To determine whether there appears to be a statistically significant relationship between sex of the driver and fatality of their accidents we would conduct a χ² analysis. Based on the results of this analysis, which of the following is the most appropriate conclusion?

A) Males appear to be at a significantly higher relative risk of fatal accidents (P > 0.05)
B) Males appear to be at a significantly higher relative risk of fatal accidents (P < 0.05)
C) Males appear to be at a significantly lower relative risk of fatal accidents (P < 0.05)
D) These data do not provide sufficient evidence that sex of driver changes the relative risk of fatal accidents (P < 0.05)

Question 22

Humans aren't the only animals that get cancer, other organisms get tumors as well and their risk may be influenced by environmental factors. An ecologist decides to study whether pollution in lakes causes cancer so he collects 100 fish from each of two lakes, one known to be polluted and the other known to be pristine. He then dissects them and determines if they have tumors in their tissues or not. His data is shown below.
?
$\begin{array}{|l|l|l|}\hline & \text { Polluted } & \text { Pristine } \\\hline \text { Tumors present } & 26 & 15 \\\hline \text { No tumors } & 74 & 85 \\\hline\end{array}$

-What proportion of all fish have tumors?

A) 15%
B) 20%
C) 26%
D) 41%

Question 23

Humans aren't the only animals that get cancer, other organisms get tumors as well and their risk may be influenced by environmental factors. An ecologist decides to study whether pollution in lakes causes cancer so he collects 100 fish from each of two lakes, one known to be polluted and the other known to be pristine. He then dissects them and determines if they have tumors in their tissues or not. His data is shown below.
?
$\begin{array}{|l|l|l|}\hline & \text { Polluted } & \text { Pristine } \\\hline \text { Tumors present } & 26 & 15 \\\hline \text { No tumors } & 74 & 85 \\\hline\end{array}$

-What is the relative risk of tumors for fish in the polluted lake compared to the pristine lake?

A) 1.11
B) 1.73
C) 1.99
D) 2.85

Question 24

Humans aren't the only animals that get cancer, other organisms get tumors as well and their risk may be influenced by environmental factors. An ecologist decides to study whether pollution in lakes causes cancer so he collects 100 fish from each of two lakes, one known to be polluted and the other known to be pristine. He then dissects them and determines if they have tumors in their tissues or not. His data is shown below.
?
$\begin{array}{|l|l|l|}\hline & \text { Polluted } & \text { Pristine } \\\hline \text { Tumors present } & 26 & 15 \\\hline \text { No tumors } & 74 & 85 \\\hline\end{array}$

-What is the odds ratio for tumors for fish in the polluted lake compared to the pristine lake?

A) 1.11
B) 1.73
C) 1.99
D) 2.85

Question 25

Humans aren't the only animals that get cancer, other organisms get tumors as well and their risk may be influenced by environmental factors. An ecologist decides to study whether pollution in lakes causes cancer so he collects 100 fish from each of two lakes, one known to be polluted and the other known to be pristine. He then dissects them and determines if they have tumors in their tissues or not. His data is shown below.
?
$\begin{array}{|l|l|l|}\hline & \text { Polluted } & \text { Pristine } \\\hline \text { Tumors present } & 26 & 15 \\\hline \text { No tumors } & 74 & 85 \\\hline\end{array}$

-Assuming a null hypothesis of no relationship between exposure to pollution and risk of developing tumors, which of the following values is closest to the expected number of fish with tumors in the polluted lake?

A) 15.5
B) 20.5
C) 25.5
D) 30.5

Question 26

Humans aren't the only animals that get cancer, other organisms get tumors as well and their risk may be influenced by environmental factors. An ecologist decides to study whether pollution in lakes causes cancer so he collects 100 fish from each of two lakes, one known to be polluted and the other known to be pristine. He then dissects them and determines if they have tumors in their tissues or not. His data is shown below.
?
$\begin{array}{|l|l|l|}\hline & \text { Polluted } & \text { Pristine } \\\hline \text { Tumors present } & 26 & 15 \\\hline \text { No tumors } & 74 & 85 \\\hline\end{array}$

-To determine whether there appears to be a statistically significant relationship between exposure to pollution and risk of developing tumors he decides to conduct a ?² analysis. When performing this analysis, which of the values below is closest to the contribution to the ?² statistic from the "No tumors : pristine" category?

A) 0.38
B) 1.48
C) 2.58
D) 3.68

Question 27

Humans aren't the only animals that get cancer, other organisms get tumors as well and their risk may be influenced by environmental factors. An ecologist decides to study whether pollution in lakes causes cancer so he collects 100 fish from each of two lakes, one known to be polluted and the other known to be pristine. He then dissects them and determines if they have tumors in their tissues or not. His data is shown below.
?
$\begin{array}{|l|l|l|}\hline & \text { Polluted } & \text { Pristine } \\\hline \text { Tumors present } & 26 & 15 \\\hline \text { No tumors } & 74 & 85 \\\hline\end{array}$

-To determine whether there appears to be a statistically significant relationship between exposure to pollution and risk of developing tumors he decides to conduct a ?² analysis. When performing this analysis, which of the values below is closest to the ?² statistic he would obtain?

A) 3.7
B) 5.7
C) 7.7
D) 9.7

Question 28

To determine whether there appears to be a statistically significant relationship between exposure to pollution and risk of developing tumors he decides to conduct a χ² analysis. Based on the results of this analysis, which of the following is the most appropriate conclusion?

A) Fish appear to be at a significantly higher risk of tumors in the polluted lake compared to the pristine lake (P < 0.05).
B) Fish appear to be at a significantly higher risk of tumors in the polluted lake compared to the pristine lake (P > 0.05).
C) Fish appear to be at a significantly lower risk of tumors in the polluted lake compared to the pristine lake (P < 0.05).
D) These data do not provide sufficient evidence that the risk of tumors differs in polluted or pristine lakes (P < 0.05).

Question 29

Consider an experiment in which adult laboratory mice were fed one of three diets: high fat, low fat, and a control diet. The mice were weighed, received these diets for 2 weeks, and then were weighed again. The table below shows the results of the experiment.
?
? $\begin{array}{|l|l|l|}\hline \text { Diet } & \text { Gained weight } & \text { Lost weight } \\\hline \text { High Fat } & 79 & 21 \\\hline \text { Low Fat } & 30 & 69 \\\hline \text { Control } & 70 & 30 \\\hline\end{array}$

-What proportion of mice in the experiment gained weight?

A) 0.40
B) 0.60
C) 0.80
D) 0.90

Question 30

Consider an experiment in which adult laboratory mice were fed one of three diets: high fat, low fat, and a control diet. The mice were weighed, received these diets for 2 weeks, and then were weighed again. The table below shows the results of the experiment.
?
? $\begin{array}{|l|l|l|}\hline \text { Diet } & \text { Gained weight } & \text { Lost weight } \\\hline \text { High Fat } & 79 & 21 \\\hline \text { Low Fat } & 30 & 69 \\\hline \text { Control } & 70 & 30 \\\hline\end{array}$

-Assuming a null hypothesis of no relationship between diet and weight gain, which of the following values is closest to the expected count of individuals in the control group that gained weight?

A) 20
B) 40
C) 60
D) 70

Question 31

Consider an experiment in which adult laboratory mice were fed one of three diets: high fat, low fat, and a control diet. The mice were weighed, received these diets for 2 weeks, and then were weighed again. The table below shows the results of the experiment.
?
? $\begin{array}{|l|l|l|}\hline \text { Diet } & \text { Gained weight } & \text { Lost weight } \\\hline \text { High Fat } & 79 & 21 \\\hline \text { Low Fat } & 30 & 69 \\\hline \text { Control } & 70 & 30 \\\hline\end{array}$

-To determine whether there appears to be a statistically significant relationship between diet and weight gain or loss we would conduct a ?² analysis. When performing this analysis, which of the values below is closest to the contribution to the ?² statistic from the "low fat : lost weight" category?

A) 6
B) 9
C) 14
D) 21

Question 32

Consider an experiment in which adult laboratory mice were fed one of three diets: high fat, low fat, and a control diet. The mice were weighed, received these diets for 2 weeks, and then were weighed again. The table below shows the results of the experiment.
?
? $\begin{array}{|l|l|l|}\hline \text { Diet } & \text { Gained weight } & \text { Lost weight } \\\hline \text { High Fat } & 79 & 21 \\\hline \text { Low Fat } & 30 & 69 \\\hline \text { Control } & 70 & 30 \\\hline\end{array}$

-To determine whether there appears to be a statistically significant relationship between diet and weight gain or loss we would conduct a ?² analysis. When performing this analysis, which of the values below is closest to the number of degrees of freedom we would use?

A) 2
B) 3
C) 4
D) 5

Question 33

Consider an experiment in which adult laboratory mice were fed one of three diets: high fat, low fat, and a control diet. The mice were weighed, received these diets for 2 weeks, and then were weighed again. The table below shows the results of the experiment.
?
? $\begin{array}{|l|l|l|}\hline \text { Diet } & \text { Gained weight } & \text { Lost weight } \\\hline \text { High Fat } & 79 & 21 \\\hline \text { Low Fat } & 30 & 69 \\\hline \text { Control } & 70 & 30 \\\hline\end{array}$

-To determine whether there appears to be a statistically significant relationship between diet and weight gain or loss we would conduct a ?² analysis. When performing this analysis, which of the values below is closest to the ?² statistic we would obtain?

A) 4
B) 14
C) 34
D) 54

Question 34

Consider an experiment in which a pharmaceutical company is testing a new drug that they hope will lower cholesterol levels. They administer three treatments: A dose of the drug, a dose of a placebo, and a control group that receives neither drug nor placebo. after 24 hours they then measured the cholesterol levels and compared the values to baseline levels measured prior to treatment. The table below shows the results of the experiment.
?? $\begin{array}{|l|l|l|}\hline \text { Treatment } & \text { Chol. lower } & \begin{array}{l}\text { Chol. increased } \\\text { or the same }\end{array} \\\hline \text { Drug } & 64 & 36 \\\hline \text { Placebo } & 51 & 49 \\\hline \text { Control } & 48 & 52 \\\hline\end{array}$

-What proportion of individuals in the experiment showed cholesterol levels that increased or stayed the same?

A) 0.38
B) 0.46
C) 0.54
D) 0.62

Question 35

Consider an experiment in which a pharmaceutical company is testing a new drug that they hope will lower cholesterol levels. They administer three treatments: A dose of the drug, a dose of a placebo, and a control group that receives neither drug nor placebo. after 24 hours they then measured the cholesterol levels and compared the values to baseline levels measured prior to treatment. The table below shows the results of the experiment.
?? $\begin{array}{|l|l|l|}\hline \text { Treatment } & \text { Chol. lower } & \begin{array}{l}\text { Chol. increased } \\\text { or the same }\end{array} \\\hline \text { Drug } & 64 & 36 \\\hline \text { Placebo } & 51 & 49 \\\hline \text { Control } & 48 & 52 \\\hline\end{array}$

-Assuming a null hypothesis of no relationship between diet and weight gain, which of the following values is closest to the expected count of individuals in the placebo group that showed lower cholesterol levels?

A) 46
B) 49
C) 51
D) 54

Question 36

Consider an experiment in which a pharmaceutical company is testing a new drug that they hope will lower cholesterol levels. They administer three treatments: A dose of the drug, a dose of a placebo, and a control group that receives neither drug nor placebo. after 24 hours they then measured the cholesterol levels and compared the values to baseline levels measured prior to treatment. The table below shows the results of the experiment.
?? $\begin{array}{|l|l|l|}\hline \text { Treatment } & \text { Chol. lower } & \begin{array}{l}\text { Chol. increased } \\\text { or the same }\end{array} \\\hline \text { Drug } & 64 & 36 \\\hline \text { Placebo } & 51 & 49 \\\hline \text { Control } & 48 & 52 \\\hline\end{array}$

-To determine whether there appears to be a statistically significant relationship between diet and weight gain or loss they would conduct a ?² analysis. When performing this analysis, which of the values below is closest to the contribution to the ?² statistic from the "drug : cholesterol lower" category?

A) 1.72
B) 1.91
C) 2.05
D) 2.21

Question 37

Consider an experiment in which a pharmaceutical company is testing a new drug that they hope will lower cholesterol levels. They administer three treatments: A dose of the drug, a dose of a placebo, and a control group that receives neither drug nor placebo. after 24 hours they then measured the cholesterol levels and compared the values to baseline levels measured prior to treatment. The table below shows the results of the experiment.
?? $\begin{array}{|l|l|l|}\hline \text { Treatment } & \text { Chol. lower } & \begin{array}{l}\text { Chol. increased } \\\text { or the same }\end{array} \\\hline \text { Drug } & 64 & 36 \\\hline \text { Placebo } & 51 & 49 \\\hline \text { Control } & 48 & 52 \\\hline\end{array}$

-To determine whether there appears to be a statistically significant relationship between the treatment and changes in cholesterol level they would conduct a ?² analysis. When performing this analysis, which of the values below is closest to the ?² value they would compare the calculated value to in order to determine significance at the 5% level?

A) 3.841
B) 5.991
C) 7.815
D) 9.488

Question 38

Consider an experiment in which a pharmaceutical company is testing a new drug that they hope will lower cholesterol levels. They administer three treatments: A dose of the drug, a dose of a placebo, and a control group that receives neither drug nor placebo. after 24 hours they then measured the cholesterol levels and compared the values to baseline levels measured prior to treatment. The table below shows the results of the experiment.
?? $\begin{array}{|l|l|l|}\hline \text { Treatment } & \text { Chol. lower } & \begin{array}{l}\text { Chol. increased } \\\text { or the same }\end{array} \\\hline \text { Drug } & 64 & 36 \\\hline \text { Placebo } & 51 & 49 \\\hline \text { Control } & 48 & 52 \\\hline\end{array}$

-To determine whether there appears to be a statistically significant relationship between the treatment and changes in cholesterol level they would conduct a ?² analysis. When performing this analysis, which of the values below is closest to the ?² statistic they would obtain?

A) 3.77
B) 4.32
C) 5.83
D) 6.94

Question 39

Sea star wasting disease kills sea stars (i.e., starfish) and has no known cause. It is currently a major problem on the West Coast and many sea stars are infected and dying. Consider a study in which a researcher is interested in whether susceptibility varies between the species. He travels to a site known to show wasting and counts the numbers of healthy and wasting individuals from three different species. His data is shown in the histogram below.
​
​
-To determine whether there appears to be a statistically significant relationship between the treatment and changes in cholesterol level they would conduct a χ² analysis. When performing this analysis, which of the following best describes the conclusion they could make from the data?

A) These data do not provide sufficient evidence that treatment type is associated with changes in cholesterol level.
B) There is a statistically significant relationship between treatment and changes in cholesterol level, the drug lowers cholesterol more than the other treatments.
C) There is a statistically significant relationship between treatment and changes in cholesterol level, the placebo lowers cholesterol more than the other treatments.
D) There is a statistically significant relationship between treatment and changes in cholesterol level, the control group showed lower cholesterol compared to the other treatments.

Question 40

Sea star wasting disease kills sea stars (i.e., starfish) and has no known cause. It is currently a major problem on the West Coast and many sea stars are infected and dying. Consider a study in which a researcher is interested in whether susceptibility varies between the species. He travels to a site known to show wasting and counts the numbers of healthy and wasting individuals from three different species. His data is shown in the histogram below.
​
​
-Assuming a null hypothesis of no relationship between species and prevalence of wasting disease, which of the following values is closest to the expected count of Solaster with wasting disease?

A) 10.69
B) 13.65
C) 15.13
D) 17.22

Question 41

Sea star wasting disease kills sea stars (i.e., starfish) and has no known cause. It is currently a major problem on the West Coast and many sea stars are infected and dying. Consider a study in which a researcher is interested in whether susceptibility varies between the species. He travels to a site known to show wasting and counts the numbers of healthy and wasting individuals from three different species. His data is shown in the histogram below.
​
​
-To determine whether there appears to be a statistically significant relationship between species and prevalence of wasting disease he would conduct a χ² analysis. When performing this analysis, which of the values below is closest to the number of degrees of freedom he would use?

A) 1
B) 2
C) 3
D) 4

Question 42

Sea star wasting disease kills sea stars (i.e., starfish) and has no known cause. It is currently a major problem on the West Coast and many sea stars are infected and dying. Consider a study in which a researcher is interested in whether susceptibility varies between the species. He travels to a site known to show wasting and counts the numbers of healthy and wasting individuals from three different species. His data is shown in the histogram below.
​
​
-To determine whether there appears to be a statistically significant relationship between species and prevalence of wasting disease he would conduct a χ² analysis. When performing this analysis, which of the values below is closest to the contribution to the χ² statistic from the "Healthy : Pycnopodia" category?

A) 0.47
B) 0.82
C) 1.59
D) 2.14

Question 43

Sea star wasting disease kills sea stars (i.e., starfish) and has no known cause. It is currently a major problem on the West Coast and many sea stars are infected and dying. Consider a study in which a researcher is interested in whether susceptibility varies between the species. He travels to a site known to show wasting and counts the numbers of healthy and wasting individuals from three different species. His data is shown in the histogram below.
​
​
-To determine whether there appears to be a statistically significant relationship between species and prevalence of wasting disease he would conduct a χ² analysis. When performing this analysis, which of the values below is closest to the χ² statistic he would obtain?

A) 3.3
B) 5.7
C) 9.5
D) 11.2

Question 44

Sea star wasting disease kills sea stars (i.e., starfish) and has no known cause. It is currently a major problem on the West Coast and many sea stars are infected and dying. Consider a study in which a researcher is interested in whether susceptibility varies between the species. He travels to a site known to show wasting and counts the numbers of healthy and wasting individuals from three different species. His data is shown in the histogram below.
​
​
-To determine whether there appears to be a statistically significant relationship between species and prevalence of wasting disease he would conduct a χ² analysis. After performing this analysis, which of the ranges below best describes the P value he would obtain?

A) P > 0.05
B) 0.05 > P > 0.025
C) 0.025 > P > 0.01
D) P < 0.01

Question 45

A microbial ecologist is interested in whether the microbial community of a pond changes when it rains. She knows that rainfall will increase the number of bacteria, but she is interested in the pattern of diversity. She collects a water sample from a pond two days before a rainfall and two days after and plates her samples on agar (a method to measure bacteria) and counts the number of colonies she observes for each of three bacteria: E. Coli, Salmonella, and Giardia. In the pre-rain sample she observes 21, 57, and 32 colonies respectively. In the post-rain sample she observes 59, 83, and 88 colonies respectively.
​

-Which of the mosaic tables shown correctly depicts this data?

A) Graph A
B) Graph B
C) Graph C
D) Graph D

Question 46

A microbial ecologist is interested in whether the microbial community of a pond changes when it rains. She knows that rainfall will increase the number of bacteria, but she is interested in the pattern of diversity. She collects a water sample from a pond two days before a rainfall and two days after and plates her samples on agar (a method to measure bacteria) and counts the number of colonies she observes for each of three bacteria: E. Coli, Salmonella, and Giardia. In the pre-rain sample she observes 21, 57, and 32 colonies respectively. In the post-rain sample she observes 59, 83, and 88 colonies respectively.
​

-Assuming a null hypothesis of no relationship between rainfall and bacterial diversity, which of the following values is closest to the expected count of

A) 39
B) 44
C) 49
D) 54

Question 47

A microbial ecologist is interested in whether the microbial community of a pond changes when it rains. She knows that rainfall will increase the number of bacteria, but she is interested in the pattern of diversity. She collects a water sample from a pond two days before a rainfall and two days after and plates her samples on agar (a method to measure bacteria) and counts the number of colonies she observes for each of three bacteria: E. Coli, Salmonella, and Giardia. In the pre-rain sample she observes 21, 57, and 32 colonies respectively. In the post-rain sample she observes 59, 83, and 88 colonies respectively.
​

-To determine whether there appears to be a statistically significant relationship between rainfall and bacterial diversity she would conduct a χ² analysis. When performing this analysis, which of the values below is closest to the contribution to the χ² statistic from the "pre-rainfall : Salmonella" category?

A) 1.01
B) 2.02
C) 3.03
D) 4.04

Question 48

A microbial ecologist is interested in whether the microbial community of a pond changes when it rains. She knows that rainfall will increase the number of bacteria, but she is interested in the pattern of diversity. She collects a water sample from a pond two days before a rainfall and two days after and plates her samples on agar (a method to measure bacteria) and counts the number of colonies she observes for each of three bacteria: E. Coli, Salmonella, and Giardia. In the pre-rain sample she observes 21, 57, and 32 colonies respectively. In the post-rain sample she observes 59, 83, and 88 colonies respectively.
​

-To determine whether there appears to be a statistically significant relationship between rainfall and bacterial diversity she would conduct a χ² analysis. When performing this analysis, which of the values below is closest to the number of degrees of freedom she would use?

A) 1
B) 2
C) 3
D) 4

Question 49

A microbial ecologist is interested in whether the microbial community of a pond changes when it rains. She knows that rainfall will increase the number of bacteria, but she is interested in the pattern of diversity. She collects a water sample from a pond two days before a rainfall and two days after and plates her samples on agar (a method to measure bacteria) and counts the number of colonies she observes for each of three bacteria: E. Coli, Salmonella, and Giardia. In the pre-rain sample she observes 21, 57, and 32 colonies respectively. In the post-rain sample she observes 59, 83, and 88 colonies respectively.
​

-To determine whether there appears to be a statistically significant relationship between rainfall and bacterial diversity she would conduct a χ² analysis. When performing this analysis, which of the values below is closest to the χ² statistic she would obtain?

A) 2.6
B) 6.2
C) 6.7
D) 7.6

Question 50

A microbial ecologist is interested in whether the microbial community of a pond changes when it rains. She knows that rainfall will increase the number of bacteria, but she is interested in the pattern of diversity. She collects a water sample from a pond two days before a rainfall and two days after and plates her samples on agar (a method to measure bacteria) and counts the number of colonies she observes for each of three bacteria: E. Coli, Salmonella, and Giardia. In the pre-rain sample she observes 21, 57, and 32 colonies respectively. In the post-rain sample she observes 59, 83, and 88 colonies respectively.
​

-To determine whether there appears to be a statistically significant relationship between rainfall and bacterial diversity she would conduct a χ² analysis. After performing this analysis, which of the ranges below best describes the P value she would obtain?

A) P > 0.05
B) 0.05 > P > 0.025
C) 0.025 > P > 0.01
D) P < 0.01

Question 51

To determine whether there appears to be a statistically significant relationship between rainfall and bacterial diversity she would conduct a χ² analysis. After performing this analysis, which of the following best describes the conclusion she could make from the data?

A) There appears to be no statistically significant relationship between rainfall and bacterial diversity.
B) There is a statistically significant relationship between rainfall and bacterial diversity, the
C) There is a statistically significant relationship between rainfall and bacterial diversity, the Salmonella is less common (relative to the other bacteria) after rainfall than before.
D) There is a statistically significant relationship between rainfall and bacterial diversity, the Giardia is less common (relative to the other bacteria) after rainfall than before.

Question 52

The relative risk and odds ratio measure similar, but distinct, things. Each has an advantage over the other so both are often calculated. For each of these two statistics, what is the advantage it has compared to the alternative?

Question 53

There are two situations having to do with expected frequencies that create problems for χ² analyses. Describe these two situations and two solutions that resolve these issues.

Question 54

What is the main benefit of the Fisher's Exact test compared to a traditional χ² analysis?

Question 55

Consider an observational study in which a sample of individuals with a certain condition are compared to a second reference group that do not have the condition. Proportions of individuals with risk factor in each group can then be compared.
(a) This type of study is called a(n) _______ - _______ study.
(b) With this type of data we can do a(n) _______ - _______ analysis, but not a(n) _______ - _______ .

Question 56

Under what circumstances are the relative risk and odds ratio most similar?