Question 1

Use the following information for questions:
In a study of 900 European American children born in 1991 ("Maternal Employment and Child Cognitive Outcomes in the First Three Years of Life: The NICHD Study of Early Child Care," Brooks-Gunn, Han, and Waldfogel, Child Development 73[2002]: 1052-1072), the authors wrote "children whose mothers worked at all by the ninth month of their life had lower [cognitive outcome] scores at 36 months than did children whose mothers did not work by that time." These results were statistically significant.
-What is the response variable in this study?
A) The age of the child
B) The cognitive outcome score of the child at 36 months
C) The working history of the mother (did or did not work during the first nine months of the child's life)
D) None of the above

Accepted Answer

The response variable in this study is the cognitive outcome score of the child at 36 months, as this is the outcome the researchers are measuring and comparing between the two groups of children (those whose mothers worked and those whose mothers did not work in the first nine months).

Question 2

Use the following information for questions:
In a study of 900 European American children born in 1991 ("Maternal Employment and Child Cognitive Outcomes in the First Three Years of Life: The NICHD Study of Early Child Care," Brooks-Gunn, Han, and Waldfogel, Child Development 73[2002]: 1052-1072), the authors wrote "children whose mothers worked at all by the ninth month of their life had lower [cognitive outcome] scores at 36 months than did children whose mothers did not work by that time." These results were statistically significant.
-What is the explanatory variable in this study?
A) The age of the child
B) The cognitive outcome score of the child at 36 months
C) The working history of the mother (did or did not work during the first nine months of the child's life)
D) None of the above

Accepted Answer

The explanatory variable is the factor that might cause a change in another variable. In this study, the working history of the mother (whether she worked or did not work during the first nine months of the child's life) is investigated to see its effect on the child's cognitive outcome scores at 36 months, making it the explanatory variable.

Question 3

Use the following information for questions:
In a study of 900 European American children born in 1991 ("Maternal Employment and Child Cognitive Outcomes in the First Three Years of Life: The NICHD Study of Early Child Care," Brooks-Gunn, Han, and Waldfogel, Child Development 73[2002]: 1052-1072), the authors wrote "children whose mothers worked at all by the ninth month of their life had lower [cognitive outcome] scores at 36 months than did children whose mothers did not work by that time." These results were statistically significant.
-Can a conclusion be made that mothers who worked during the first nine months after having a child caused the lower scores seen at 36 months?
A) A cause and effect relation might be concluded because of the large sample size and the long follow-up period (3 years).
B) A cause and effect relation might be concluded because the results were statistically significant.
C) A cause and effect relation cannot be concluded because the study was an observational study.
D) A cause and effect relation cannot be concluded because the study was a case-control study.

Accepted Answer

C) A cause and effect relation cannot be concluded because the study was an observational study.

Question 4

Use the following information for questions:
 A study of 42 patients with carpal tunnel syndrome (symptoms of burning numbness in the wrist to difficulty making a fist) was done ("Yoga based intervention for carpal tunnel syndrome," Garfinkel et al, JAMA 1998; 280:1601-1603). Subjects were randomly assigned to a yoga group or a control (where they were offered a wrist splint to supplement their current treatment). Results showed that subjects in the yoga group had significant improvement in grip strength, while subjects in the control group did not.
-What is the response variable in the study?
A) The improvement in grip strength
B) The treatment group (either Yoga or control group)
C) The severity of carpal tunnel syndrome
D) The age of the patient.

Accepted Answer

The response variable in the study is the outcome that the researchers are measuring to see if it changes in response to the experimental conditions. In this case, it's the improvement in grip strength among the subjects, as the study aimed to assess the effect of yoga-based intervention on this particular aspect of carpal tunnel syndrome.

Question 5

Use the following information for questions:
 A study of 42 patients with carpal tunnel syndrome (symptoms of burning numbness in the wrist to difficulty making a fist) was done ("Yoga based intervention for carpal tunnel syndrome," Garfinkel et al, JAMA 1998; 280:1601-1603). Subjects were randomly assigned to a yoga group or a control (where they were offered a wrist splint to supplement their current treatment). Results showed that subjects in the yoga group had significant improvement in grip strength, while subjects in the control group did not.
-What is the explanatory variable in the study?
A) The improvement in grip strength
B) The treatment group (either Yoga or control group)
C) The severity of carpal tunnel syndrome
D) The age of the patient.

Accepted Answer

The explanatory variable in the study is the treatment group (either Yoga or control group), as it is the variable that is manipulated to observe its effect on the outcome, which in this case is the improvement in grip strength.

Question 6

Use the following information for questions:
 A study of 42 patients with carpal tunnel syndrome (symptoms of burning numbness in the wrist to difficulty making a fist) was done ("Yoga based intervention for carpal tunnel syndrome," Garfinkel et al, JAMA 1998; 280:1601-1603). Subjects were randomly assigned to a yoga group or a control (where they were offered a wrist splint to supplement their current treatment). Results showed that subjects in the yoga group had significant improvement in grip strength, while subjects in the control group did not.
-Can a conclusion that yoga caused the improvement in grip strength be made?
A) A cause and effect relation might be concluded because the study had a control group.
B) A cause and effect relation might be concluded because the study was a randomized experiment.
C) A cause and effect relation cannot be concluded because of the small sample size.
D) A cause and effect relation cannot be concluded because not all subjects in the control group accepted the splint.

Accepted Answer

A cause and effect relation might be concluded because the study was a randomized experiment. Randomization helps to ensure that any differences observed between the groups are due to the treatment (yoga) and not to other factors.

Question 7

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 43 sedentary adults between the ages of 50 and 76 were randomly assigned to either an exercise program four times a week for 16 weeks or they continued to be sedentary (King, et al, JAMA, January 1, 1997,pp 32-37). The exercise group slept an average of 42 minutes a night longer than the control group.
-What is the response variable in the study?
A) Amount of food eaten (calories) per day
B) Following an exercise program four times a week for 16 weeks (or not)
C) Amount of sleep per night
D) Age

Accepted Answer

The response variable in the study is the outcome that the researchers are measuring to see if it is affected by the treatment, which in this case is the amount of sleep per night.

Question 8

Use the following information for questions:
 43 sedentary adults between the ages of 50 and 76 were randomly assigned to either an exercise program four times a week for 16 weeks or they continued to be sedentary (King, et al, JAMA, January 1, 1997,pp 32-37). The exercise group slept an average of 42 minutes a night longer than the control group.
-What is the explanatory variable in the study?
A) Amount of food eaten (calories) per day
B) Following an exercise program four times a week for 16 weeks (or not)
C) Amount of sleep per night
D) Age

Accepted Answer

The explanatory variable is the one that is manipulated or varied to observe its effect on another variable. In this study, the variable that was manipulated is whether participants followed an exercise program four times a week for 16 weeks or not.

Question 9

Use the following information for questions:
 43 sedentary adults between the ages of 50 and 76 were randomly assigned to either an exercise program four times a week for 16 weeks or they continued to be sedentary (King, et al, JAMA, January 1, 1997,pp 32-37). The exercise group slept an average of 42 minutes a night longer than the control group.
-Can a conclusion that the exercise program caused more sleep?
A) A cause and effect relation might be concluded because the study had a control group.
B) A cause and effect relation might be concluded because the study was a randomized experiment.
C) A cause and effect relation cannot be concluded because the study was an observational study.
D) A cause and effect relation cannot be concluded because diet was not controlled.

Accepted Answer

A cause and effect relation might be concluded because the study was a randomized experiment. Random assignment of participants to either the exercise program or the control group helps to ensure that any differences observed (such as the average increase in sleep duration) are due to the intervention itself rather than other variables.

Question 10

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Twenty volunteers were assigned at random to one of two groups (10 people in each group). One group would take Vitamin C for two weeks, while the second group would take a placebo. At the end of the study, the proportion of colds in the two groups will be compared.
-What is the response variable in the study?
A) Getting a cold (or not)
B) Taking Vitamin C (or a Placebo)
C) Getting 8 hours of sleep a night (or not)
D) Exposure to other people with colds (or not)

Accepted Answer

The response variable is the outcome that the researchers are measuring to see if it changes in response to the experimental conditions, which in this case is whether or not participants get a cold.

Question 11

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Twenty volunteers were assigned at random to one of two groups (10 people in each group). One group would take Vitamin C for two weeks, while the second group would take a placebo. At the end of the study, the proportion of colds in the two groups will be compared.
-What is the explanatory variable in the study?
A) Getting a cold (or not)
B) Taking Vitamin C (or a Placebo)
C) Getting 8 hours of sleep a night (or not)
D) Exposure to other people with colds (or not)

Accepted Answer

The explanatory variable is the one that is manipulated by the researchers to observe its effect on the outcome. In this study, the manipulation involves whether participants take Vitamin C or a placebo, making it the explanatory variable.

Question 12

Use the following information for questions:
Twenty volunteers were assigned at random to one of two groups (10 people in each group). One group would take Vitamin C for two weeks, while the second group would take a placebo. At the end of the study, the proportion of colds in the two groups will be compared.
-Can a conclusion that taking Vitamin C causes a change in the risk of a cold?
A) A cause and effect relation might be concluded because the study had a control group.
B) A cause and effect relation might be concluded because the study was a randomized experiment.
C) A cause and effect relation cannot be concluded because the study was an observational study.
D) A cause and effect relation cannot be concluded because exposure to other people with colds was not controlled.

Accepted Answer

A cause and effect relation might be concluded because the study was a randomized experiment. Random assignment of participants to the treatment or control group helps to ensure that any differences observed at the end of the study are due to the treatment itself (in this case, Vitamin C) and not to other factors.

Question 13

Use the following information for questions:
 A random sample of 500 students showed a statistically significant relationship between where the students usually sat in class (front, middle, or back) and grade point average (GPA).
-What is the response variable in the study?
A) Where a student typically sits in class (front, middle, or back)
B) Grade point average (GPA)
C) Class standing (freshman, sophomore, junior, or senior)
D) Gender (Male or Female)

Accepted Answer

The response variable in the study is the outcome variable that the researchers are interested in examining for changes or differences, which in this case is the Grade Point Average (GPA) of the students.

Question 14

Use the following information for questions:
 A random sample of 500 students showed a statistically significant relationship between where the students usually sat in class (front, middle, or back) and grade point average (GPA).
-What is the explanatory variable in the study?
A) Where a student typically sits in class (front, middle, or back)
B) Grade point average (GPA)
C) Class standing (freshman, sophomore, junior, or senior)
D) Gender (Male or Female)

Accepted Answer

The explanatory variable is the one that is thought to affect the outcome of the study. In this case, where a student typically sits in class is being studied to see how it affects their GPA, making it the explanatory variable.

Question 15

Use the following information for questions:
 A random sample of 500 students showed a statistically significant relationship between where the students usually sat in class (front, middle, or back) and grade point average (GPA).
-Can a conclusion that where a student sits in the classroom causes a change in GPA?
A) A cause and effect relation might be concluded because the results were statistically significant.
B) A cause and effect relation might be concluded because the study was a randomized experiment.
C) A cause and effect relation cannot be concluded because the study was an observational study.
D) A cause and effect relation cannot be concluded because seating preference was self-reported.

Accepted Answer

A cause and effect relationship cannot be concluded from an observational study because it does not control for other variables that might influence the outcome. The study's design does not allow for the determination of causality, only association.

Question 16

A random sample of 5000 students were asked whether they prefer a 10 week quarter system or a 15 week semester system. Of the 5000 students asked, 500 students responded. The results of this survey ________
A) can be generalized to the entire student body because the sampling was random.
B) can be generalized to the entire student body because the margin of error was 4.5%.
C) cannot be generalized to the entire student body because the non-response rate was 90%.
D) cannot be generalized to the entire student body because the margin of error was 4.5%.

Accepted Answer

The high non-response rate of 90% indicates that the sample may not be representative of the entire student body, making it difficult to generalize the results.

Question 17

Use the following information for questions:
 A random sample of 100 students living in dormitories was selected to see whether students in dormitories were satisfied with the food being served in the cafeteria.
-The conservative margin of error for the sample of 100 students is
A) 1%.
B) 5%.
C) 10%.
D) none of the above.

Accepted Answer

The answer of Use the following information for questions:
 A...

Question 18

Use the following information for questions:
 A random sample of 100 students living in dormitories was selected to see whether students in dormitories were satisfied with the food being served in the cafeteria.
-An additional group of 10 students, not selected in the sample, asked to be included so that their opinions could be heard. Adding these students to the sample
A) is a good idea because the margin of error would decrease.
B) is a good idea because students who have a strong opinion about the food should be represented in the sample.
C) is not a good idea because the margin of error would increase.
D) is not a good idea because the resulting sample may not be representative of the population of all students living in dormitories.

Accepted Answer

Adding students to the sample who specifically asked to be included could introduce bias, as these students may have stronger opinions (either positive or negative) about the cafeteria food compared to the general population of students living in dormitories. This could result in a sample that is not representative of the overall student population in dormitories, affecting the validity of the study's findings.

Question 19

Use the following information for questions:
 A random sample of 600 students was asked whether student fees should be used to construct a new football stadium.
-The conservative margin of error for the sample of 600 students is
A) 0.2%.
B) 4%.
C) 5%.
D) none of the above.

Accepted Answer

The conservative margin of error for a proportion in a sample size (n) can be calculated using the formula for a 95% confidence level as 1/sqrt(n). For n = 600, the margin of error is 1/sqrt(600) ≈ 0.04 or 4%.

Question 20

Use the following information for questions:
 A random sample of 600 students was asked whether student fees should be used to construct a new football stadium.
-An additional group of 5 football players, not selected in the sample, asked to be included so that their opinions could be heard. Adding these students to the sample
A) is a good idea because the margin of error would decrease.
B) is a good idea because students who have a strong opinion about the issue should be represented in the sample.
C) is not a good idea because the margin of error would increase.
D) is not a good idea because the resulting sample may not be representative of all students.

Accepted Answer

Adding a specific group with a strong interest in the outcome (football players) to a random sample can bias the results, making the sample less representative of the overall student population.

Quiz 17: Turning Information Into Wisdom

Use the following information for questions: A random sample of 500 students showed a statistically significant relationship between where the students usually sat in class (front, middle, or back) and grade point average (GPA) . -What is the response variable in the study?

Use the following information for questions: A random sample of 500 students showed a statistically significant relationship between where the students usually sat in class (front, middle, or back) and grade point average (GPA) . -What is the explanatory variable in the study?

A random sample of 5000 students were asked whether they prefer a 10 week quarter system or a 15 week semester system. Of the 5000 students asked, 500 students responded. The results of this survey ________

Use the following information for questions: A random sample of 100 students living in dormitories was selected to see whether students in dormitories were satisfied with the food being served in the cafeteria. -The conservative margin of error for the sample of 100 students is

Use the following information for questions: A random sample of 600 students was asked whether student fees should be used to construct a new football stadium. -The conservative margin of error for the sample of 600 students is