Question 1

block

Accepted Answer

A group of experimental units that are known before the experiment to be similar in some way that is expected to affect the response to the treatments.

Answer

In a completely randomized design, the experimental units are assigned to the treatments completely at random.

Answer

A common experimental design for comparing two treatments that uses blocks of size 2. In some matched pairs designs, two very similar experimental units are paired and the two treatments are randomly assigned within each pair. In others, each experimental unit receives both treatments in a random order.

Answer

The random assignment of experimental units to treatments is carried out separately within each block.

Question 2

randomized block design

Accepted Answer

The random assignment of experimental units to treatments is carried out separately within each block.

Answer

A common experimental design for comparing two treatments that uses blocks of size 2. In some matched pairs designs, two very similar experimental units are paired and the two treatments are randomly assigned within each pair. In others, each experimental unit receives both treatments in a random order.

Answer

In a completely randomized design, the experimental units are assigned to the treatments completely at random.

Answer

A group of experimental units that are known before the experiment to be similar in some way that is expected to affect the response to the treatments.

Question 3

matched pairs design

Accepted Answer

A common experimental design for comparing two treatments that uses blocks of size 2. In some matched pairs designs, two very similar experimental units are paired and the two treatments are randomly assigned within each pair. In others, each experimental unit receives both treatments in a random order.

Answer

A group of experimental units that are known before the experiment to be similar in some way that is expected to affect the response to the treatments.

Answer

The random assignment of experimental units to treatments is carried out separately within each block.

Answer

In a completely randomized design, the experimental units are assigned to the treatments completely at random.

Question 4

In which of the following experiments should matching be used for simple random selection?

Accepted Answer

You want to study the effect of doodling on mood for different ages and artistic abilities.

Answer

You want to study the effect of ice cream consumption on stress for people in your city.

Answer

You want to study the effect of dancing lessons on self-confidence for high school students.

Answer

You want to test the effect of glasses size on ability to make friends for different genders.

Question 5

In a study, researchers sample a group of 40 randomly selected males and another group of 40 randomly selected females. These two groups are randomly assigned to be in one of two new groups. In the first group, participants drink caffeinated soda for five days and then run three miles at the end of each day. In the second, participants drink a decaf version of the same soda for five days and then run three miles at the end of each day. Neither the participants nor researchers know which people are receiving caffeinated soda during the study. The participants who drink caffeinated drinks run faster for the first two days, and then their performances decreases when compared to the decaf group until day 5, when they are significantly slower. For the above study, researchers want to consider for age as well as gender. Which of the following studies will best do satisfy this request?

Accepted Answer

Conduct an experiment that matches participants by age, gender, and caffeine-dependence, and have them do the same experiment.

Answer

Conduct an experiment that matches participants by age and gender, and have them do the same experiment.

Answer

Conduct an experiment that uses simple random sampling so that age and gender are not confounding variables.

Answer

Conduct an experiment that uses cluster random sampling, where the clusters are men and women of certain age groups.

Question 6

A randomized block design will be used in an experiment to compare two lotions that protect people from getting sunburned. Which of the following should guide the formation of the blocks?

Accepted Answer

Participants within each block should be as similar as possible with respect to how easily they get sunburned

Answer

Participants should be kept blind as to which block they are in.

Answer

Participants should be randomly assigned to the blocks.

Answer

Participants in the same block should receive the same lotion.

Question 7

To compare the effectiveness of two treatments, researchers conducted a well-designed experiment using a randomized block design in which the subjects were blocked by age-group (under 40 years and 40 years or older). Which of the following must be true about the randomized block design of the experiment?

Accepted Answer

Treatments are randomly assigned to subjects within each block.

Answer

The number of subjects in each block is different

Answer

The experiment uses a matched-pairs design, where subjects from one block are paired with subjects from the other block

Answer

The design cannot have a control group because subjects are blocked by age-group.

Question 8

A dog food company wishes to test a new high-protein formula for puppy food to determine whether it promotes faster weight gain than the existing formula for that puppy food. Puppies participating in an experiment will be weighed at weaning (when they begin to eat puppy food) and will be weighed at one-month intervals for one year. In designing this experiment, the investigators wish to reduce the variability due to natural differences in puppy growth rates. Which of the following strategies is most appropriate for accomplishing this?

Accepted Answer

Block on dog breed and randomly assign puppies to existing and new formula groups within each breed

Answer

Stratify on geographic location of the puppies and randomly sample puppies within each geographic area. Then assign puppies by geographic area to either the existing or the new formula

Answer

Block on geographic location and randomly assign puppies to existing and new formula groups within each geographic area.

Answer

Stratify on dog breed and randomly sample puppies within each breed. Then assign puppies by breed to either the existing or the new formula.

Question 9

You work for an advertising agency that is preparing a new television commercial to appeal to women. You have been asked to design an experiment to compare the effectiveness of three versions of the commercial. Each subject will be shown one of the three versions and then asked her attitude toward the product. You think there may be large differences between women who are employed outside the home and those who are not. Because of these differences, you should use

Accepted Answer

a block design

Answer

a stratified design.

Answer

a multistage sample.

Answer

a completely randomized design.

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