Worksheet on Statistical design

Worksheet on Statistical design

Worksheet on Statistical design

Worksheet on Statistical design

 

1.Bob has a severe cold. His roommate takes a garlic tablet every morning and has not had a cold in two years. Bob’s aunt also has a friend who takes garlic tablets daily and has not had a cold in more than a year.  Based on these data, Bob decides to start taking garlic tablets as soon as his cold clears up. What type of study is Bob’s decision based on?
A)Anecdotal evidence.
B)An observational study based on available data.
C)An observational study based on a sample survey.
D)An experiment.

 

2.A study is designed to determine whether grades in a statistics course could be improved by offering special review material. The 250 students enrolled in a large introductory statistics class are also enrolled in one of 20 lab sections. The 20 lab sections are randomly divided into 2 groups of 10 lab sections each. The students in the first set of 10 lab sections are given extra review material during the last 15 minutes of each weekly lab session. The students in the remaining 10 lab sections receive the regular lesson material, without the extra review material. The grades of the students who reviewed weekly were higher, on average, than the students who did not review every week. What type of study is this?
A)An observational study.
B)An experiment, but not a double-blind experiment.
C)A double-blind experiment.
D)A matched-pairs experiment.

 

3.In order to assess the effects of exercise on reducing cholesterol, a researcher sampled 50 people from a local gym who exercise regularly and 50 people from the surrounding community who, were assumed, do not exercise regularly.  Each subject reported to a clinic to have their cholesterol measured.  The subjects were unaware of the purpose of the study, and the technician measuring the cholesterol was not aware of whether the subject exercises regularly or not.  What type of study is this?
A)An observational study.
B)An experiment, but not a double-blind experiment.
C)A double-blind experiment.
D)A matched-pairs experiment.

 

Use the following to answer questions 4–6.

A researcher is studying the relationship between sugar consumption and weight gain. Twelve volunteers were randomly assigned to one of two groups. The first group of five participants was put on a diet low in sugar and the second group of the remaining seven participants received 10% of their calories from sugar. After 8 weeks, weight gain was recorded from each participant.

 

4.What type of study is this?
A)An observational study.
B)An experiment, but not a double-blind experiment.
C)A double-blind experiment.
D)A matched-pairs experiment.

 

5.Which of the following basic principles of statistical design was not used in this experiment?
A)Control
B)Randomization
C)Repetition
D)Blinding

 

6.Each of the 12 volunteers receives a label: 01 through 12. Use the list of random digits below to determine the labels of the first five participants selected who were put on a low-sugar diet. Start at the beginning of the list and use double-digit labels.

81507  27102  56027  55892  33063  41842  81868  71035  09001  23367  49497

A)8, 1, 5, 0, 7
B)8, 1, 5, 7, 2
C)2, 6, 10, 9, 12
D)2, 2, 6, 10, 9

 

Use the following to answer questions 7-9

Twelve people, who suffer from chronic fatigue syndrome, volunteer to take part in an experiment to see if shark fin extract will increase one’s energy level.  Eight of the volunteers are men and four are women.  Half of the volunteers are to be given shark fin extract twice a day and the other half a placebo twice a day.  We wish to make sure that four men and two women are assigned to each of the treatments, so we decide to use a block design with the men forming one block and the women the other.

 

7.For which reason is a block design appropriate in this experiment?
A)Gender equity is an important legal consideration in this study.
B)We believe men and women will respond differently to treatments.
C)We want the conclusions to apply equally to men and women.
D)All of the above.

 

8.Suppose one of the researchers is responsible for measuring if a subject displays an increase in energy level.  What design principle should be added to this experiment?
A)Two placebos.
B)Use a stratified sampling design to assign subjects to treatments.
C)Use fewer subjects but observe them more frequently.
D)Conduct the study as a double-blind experiment.
9.Each of the 8 men receives a label: 1 through 8. Use the list of random digits below to determine the labels of the four men who are to be given shark fin extract twice a day. Start at the beginning of the list and use single-digit labels.

 

02902  28461  80624  10082  56872  88033  48932  03845  98302 83623  36704

 

A)0, 2, 9, 0
B)0, 2, 9, 8
C)2, 8, 4, 6
D)2, 9, 8, 4

 

 

 10) Many colleges offer online versions of some of their courses that are also taught in the classroom. It often happens that the students who enroll in the online courses perform better on the course exams. Does that mean that online instruction is more effective than classroom teaching? Suggest some student characteristics that could be confounded with online versus classroom.

 

 

 

11) Children who watch many hours of television get lower grades in school, on the average, than those who watch less TV. Explain clearly why this fact does not show that watching TV causes poor grades. In particular, suggest some other variables that may be confounded with heavy TV viewing and may contribute to poor grades.

 

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