Quiz 2

1.  What is a closed​ question? What is an open​ question? Discuss the advantages and disadvantages of each type of question.

What is a closed​ question? What is an open​ question?

1. A closed question is a​ free-response question, whereas an open question has fixed choices for answers.
2. A closed question has fixed choices for​ answers, whereas an open question is a​ free-response question.
3. A closed question always has yes or no​ answers, whereas an open question is a​ free-response question.
4. A closed question has many correct​ answers, whereas an open question has only one correct answer.

Discuss the advantages and disadvantages of each type of question.

1. Closed questions are easier to​ analyze, because they usually gather more accurate data. Open questions limit the​ responses, but are harder to analyze since not every viewpoint will be covered.
2. Closed questions are easier to​ analyze, but limit the responses. Open questions allow respondents to state exactly how they​ feel, but are harder to analyze due to the variety of answers and possible misinterpretation of answers.
3. Closed questions allow respondents to state exactly how they​ feel, but are harder to analyze due to the variety of answers and possible misinterpretation of answers. Open questions are easier to​ analyze, but limit the responses.
4. Closed questions are harder to​ analyze, because they limit the responses. Open questions allow respondents to state exactly how they​ feel, but are easier to analyze due to the variety of answers.

2.  What does it mean when a part of the population is​ under-represented?

Choose the correct answer below.

1. A part of the population is​ under-represented when it is proportionally smaller in its population than in a sample.
2. A part of the population is​ under-represented when it is proportionally smaller in a sample than in its population.
3. A part of the population is​ under-represented when their answers on a survey tend not to reflect their true feelings.
4. A part of the population is​ under-represented when individuals selected to be in the sample who do not respond to the survey have different opinions from those who do.

3.  The manager of a shopping mall wishes to expand the number of shops available in the food court.  She has a market researcher survey the first 110 customers who come into the food court during weekday mornings to determine what types of food the shoppers would like to see added to the food court. Complete parts​ (a) and​ (b) below.

​(a) The survey has bias. Determine whether the flaw is due to the sampling method or the survey itself. For biased​ surveys, identify the cause of the error.

What is the cause of the​ bias?

1. Response bias
2. Nonresponse
3. Sampling bias

​(b) Suggest a remedy to the problem.

Which of the following is the best way to remedy this​ problem?

1. Increase the sample size so that more people respond to the question.
2. Reword the question so that it is balanced.
3. Ask customers throughout the day on both weekdays and weekends.

4. The following survey has bias.

​(a) Determine the type of bias.

​(b) Suggest a remedy.

A retail store manager wants to conduct a study regarding the shopping habits of his customers. He selects the first 60 customers who enter his store on a Saturday morning.

​(a) What is the type of​ bias?

1. Response bias
2. Nonresponse bias
3. Sampling bias

 ​(b) What is a possible​ remedy?

1. Conduct face-to-face or telephone interviews.
2. Use systematic random sampling.
3. Reword the question.

5.  A survey mailed to residents of a town has a response rate of less than 2%.

A survey that pertains to feelings about federal income tax does not include high-income earners.

In a survey, college students are asked to disclose the number of hours they study.

A survey conducted by revenue collection agents asks taxpayers to identify sources of fraudulent deductions.

6.  Explain the difference between a​ single-blind and a​ double-blind experiment.  Choose the correct answer below.

1. In a​ single-blind experiment, there is a control group. In a​ double-blind experiment, there is both a control group and a placebo treatment is used.
2. A single blind experiment is one in which each experimental unit is randomly assigned to a treatment. A​ double-blind experiment is one in which similar experimental units are grouped together and the experimental units within each block are randomly assigned to treatments.
3. In a​ single-blind experiment, the researcher does not know what the response variable is. In a​ double-blind experiment, neither the subject nor the researcher knows what the response variable is.
4. In a​ single-blind experiment, the subject does not know which treatment is received. In a​ double-blind experiment, neither the subject nor the researcher in contact with the subject knows which treatment is received.

7.  To help assess student learning in her developmental physics ​courses, a physics professor at a university implemented​ pre- and​ post-tests for her developmental physics students. A​ knowledge-gained score was obtained by taking the difference of the two test scores.

What type of experimental design is​ this?

1. Completely randomized design
2. Randomized block design
3. Matched pair
4. ​Case-control

What is the response variable in this​ experiment?

1. The score on the pretest
2. Difference in test scores
3. Total in test scores
4. The score on the posttest

What is the​ treatment?

1. Background of student
2. Physics scores
3. Physics course
4. Type of school

8.  Researchers wanted to evaluate whether​ ginkgo, an​ over-the-counter herb marketed as enhancing​ memory, improves memory in elderly adults as measured by objective tests. To do​ this, they recruited 88 men and 130 women older than 55 years and in good health. Participants were randomly assigned to receive​ ginkgo, 40 milligrams​ (mg) 3 times per​ day, or a matching placebo. The measure of memory improvement was determined by a standardized test of learning and memory. After 6 weeks of​ treatment, the data indicated that ginkgo did not increase performance on standard tests of​ learning, memory,​ attention, and concentration. These data suggest​ that, when taken following the​ manufacturer’s instructions, ginkgo provides no measurable increase in memory or related cognitive function to adults with healthy cognitive function. Complete parts​ (a) through​ (g) below.

(a) What type of experimental design is​ this?

1. Completely randomized design
2. Cohort study
3. ​Case-control study
4. Randomized block design.
5. ​Matched-pairs design

​(b) What is the population being​ studied?

1. All adults in good health
2. Adults older than 55 years
3. All adults
4. Adults older than 55 years and in good health

 ​(c) What is the response variable in this​ study?

1. The age of the participants in the study
2. The score on the standardized test of learning and memory
3. The 40 mg 3 times a day
4. The number of men and women in the study

​(d) What is the factor that is set to predetermined​ levels?

1. The health of the adult
2. The​ drug: 40 mg 3 times a day or a matching placebo
3. The age of the adult
4. The number of men and women in the study

What are the​ treatments?

1. The number of men and women in the study
2. The 40 mg of the drug 3 times a day or a matching placebo
3. The standardized test
4. The age and health of the adult

​(e) Identify the experimental units. Choose the correct answer below.

1. The placebo and 40 mg of the herb
2. The 88 men and 130 women older than 55 who are in good health that participated in the study
3. Elderly adults
4. Men and women older than 55 who are in good health

​(f) What is the control group in this​ study?

1. The men serve as the control group because this group corresponds to the herb that is being tested.
2. The placebo group serves as the control group because this group corresponds to the reference point that will be compared to the other group.
3. The women serve as the control group because this group corresponds to the herb that is being tested.
4. The herb group serves as the control group because this group corresponds to the reference point that will be compared to the other group.

9.  A researcher has decided to test the effectivness of a drug meant to reduce high cholesterol through a completely randomized design. She has obtained 9 volunteers with high​ cholesterol: Amanda,​ Brian, Christine,​ David, Emily,​ Fred, George,​ Heather, and Ivan. Number the volunteers 1 through​ 9, alphabetically. Use the second row of digits in the random number table below to randomly assign 3 of the volunteers to the experimental group​ (ignore zeros). The remaining volunteers will go into the control group. List the individuals in each group.

What are the numbers of the three volunteers​ selected? ​(List the terms in the same order they appear in the original​ list.)

List the three indivduals assigned to the experimental group. Choose the correct answer below.

1. Fred, George, Brian
2. Heather, George, Brian
3. Fred, George, Heather
4. Fred, Heather, Brian

List the remaining indivduals assigned to the control group. Choose the correct answer below.

1. David, Ivan, Emily, Christine, Amanda, Heather
2. David, Ivan, Emily, Christine, Amanda, George
3. Fred, George, Brian

10. Does the level of octane in gasoline affect gas​ mileage? To answer this​ question, an automotive engineer obtains 60 cars. Twenty of the cars are​ compact, 20 are full​ size, and 20 are sport utility vehicles​ (SUVs). Design an experiment for the engineer.What type of experimental design should the engineer​ use?

1. ​Case-control
2. Randomized block design
3. Matched pair
4. Completely randomized design