Regular Block Design vs. Matched Pairs Design

In the previous problem, supposed that the researchers suspected that women over the age of 55 may respond differently to the treatment. Given that a random sample of 40,000 women over the age of 45 has already been chosen, the study would have been improved by:

• a stratified sample, with strata determined by age.

• a stratified sample, with strata determined by gender.

• a block design, with blocks determined by age.

• a block design, with blocks determined by gender.

• a double-blind completely randomized design.

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Researchers were interested to know whether internal vehicle temperatures vary by outside temperatures. To evaluate this, temperature rise was measured continuously over a 60-minute period in a dark SUV on 16 different clear, sunny days with outside temperatures ranging from 72^oF to 96^oF. The researchers' method of analysis is best described as:

• a census.

• a survey.

• an observational study.

• a randomized comparative experiment.

• a single-blind randomized comparative experiment.

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Runners after an ultramarathon commonly develop respiratory infections. We want to know if taking 600 milligrams of vitamin C daily will reduce these infections. Researchers randomly assigned 100 ultramarathon runners to receive either vitamin C or placebo. All subjects were watched for 14 days after the big race to see if infections developed. The type of design used here?

• matched pairs
• randomized block
• completely randomized
• stratified 

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In order to perform an experiment using 60 members of a gym, I first divide the list of members into men and women because I feel that the results will be different based on gender. I then randomly choose 30 men and 30 women. I assign half of the men to the treatment group and half to the control group. I repeat this procedure with the women. This is an example of a:

• randomized comparative design
• blocking design
• matched pairs design
• double blind simple random sample

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A market research company wishes to find out whether the population of students at a university prefers Starbucks or Dunkin Donuts. A random sample of students is selected, and each student is asked first to try both but the order they try them is randomly decided with a coin toss (heads: Starbucks, then Dunkin. tails: vice versa). They then indicate which brand they prefer. This is an example of

• a completely randomized experiment
• an observational study
• a stratified sample
• a matched pairs experiment

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True or False: An example of a matched pair experimental design is having one twin receive treatment A and the second twin receive treatment B

• True
• False

True or False: An example of a matched pair experimental design is comparing a person's performance on a task before they receive the treatment and after they receive the treatment

• True
• False

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A researcher randomly selected 30 people to participate in a study to investigate which of two materials, A or B, used in the heels of sneakers will last longer. The researcher is considering two design types for the study.

Design 1: Randomly assign 15 participants to wear sneakers with material A on their left feet and material B on their right feet. The remaining participants will wear sneakers with material B on their left feet and material A on their right feet.

Design 2: Randomly assign 15 participants to wear sneakers with material A on both feet and the remaining participants to wear sneakers with material B on both feet.

Which of the following best describes each design?

• Design 1 is a completely randomized design, and design 2 is a matched pairs design.

• Design 1 is a matched pairs design, and design 2 is a completely randomized design.

• Design 1 is a matched pairs design, and design 2 is a matched pairs design.

• Design 1 is a completely randomized design, and design 2 is a completely randomized design.

• Design 1 is a completely randomized design, and design 2 is a randomized block with materials as blocks.

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The two graduates with the greatest GPA from each of 14 randomly selected law schools were recruited to investigate a new method of preparation for a law exam. For each school, one student was randomly assigned to prepare using the standard method and the other student was assigned to prepare using the new method. At the end of the preparation, all 28 students were given the same exam, and their scores were recorded.

Which of the following best describes why a matched-pairs design is an appropriate design for the investigation?

• Each graduate was randomly assigned to one method.

• The law schools were randomly selected.

• Each method served as a block.

• The sample size was less than 30.

• Each law school served as a block, and the graduates were paired within each law school and randomly assigned to one of the two methods.

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A pottery school wants to study whether the glaze of stoneware bowls is affected by the temperature used to harden the bowls. The study will use 3 different types of clay because glaze can affect different clay in different ways. Eight bowls will be made with each clay type for a total of 24 bowls, and 4 different temperatures will be used. What is the best design to use for the study?

• A completely randomized design. Randomly assign temperatures so that 6 bowls are glazed at each temperature.

• A completely randomized design. Randomly assign temperatures so that 2 bowls of each clay type are glazed at each temperature.

• A randomized block design. Randomly assign temperatures so that 6 bowls are glazed at each temperature.

• A randomized block design. Randomly assign temperatures so that 2 bowls of each clay type are glazed at each temperature.

• A matched pairs design. Randomly assign temperatures so that 2 bowls of each clay type are glazed at each temperature.

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