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4.1.7Quiz: Designs for Experiments (100%)

Terms in this set (10)

You've read a story in the New York Times claiming that individuals who engage in aerobic exercise for at least an hour a day demonstrate fewer symptoms of depression.
matched pairs before and after design
Say you're designing an experiment that looks at the effect of different types of newly developed fish food on the growth rate of the fish. The treatments are new food A and new food B; the control is the old food. You believe that the effects of the different types of food on fish growth will vary for goldfish vs. tiger fish vs. guppies. How could you design an experiment so that you're blocking on the species of fish?
First separate the fish into the three species. Then within each species, randomly assign each fish to a treatment.
You're designing an experiment that looks at the effect of different types of newly developed fish food on the growth rate of three species of fish: tiger fish, guppies, and goldfish. The treatments are new food #1, new food #2, and old food. For a randomized block design, blocked on species of fish, how many treatment groups would you have? (Think of "old food" as one of the treatments.)
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Let's say you're interested in the effects on boys of different dosage levels of a new drug for the treatment of Attention Deficit Disorder (ADD). You set up an experiment to consider the factor of dosage with two levels (300 mg vs. 500 mg). What would be the different treatment groups of the experiment within each block?
Three groups: placebo drug/300 mg of new drug/500 mg of new drug
50 boys and 50 girls with ADD (Attention Deficit Disorder) were selected for an experiment to test a new drug for the treatment of ADD. Half of the boys and half of the girls were selected at random to receive the new drug, and the other half of each group received a placebo. A reduction in symptoms of ADD was measured for each subject. The basic design of this experiment is:
randomized block, blocked by gender.
An experiment was conducted to compare the mean reaction times to two types of traffic signs: No Left Turn and Left Turn Only. Ten drivers were included in the experiment. Each driver was presented with 40 traffic signs— 20 No Left Turn and 20 L
matched pairs before and after design i
he following diagram describes an experiment in which subjects have been divided into three groups. Each of the three groups is randomly assigned to one of two treatments.
The design of this experiment is a:

randomized block design, blocked on race.
An experiment was conducted in which a researcher first administered a survey on depression and self-esteem to 100 individuals and then taught them some proper techniques of aerobic exercise. The 100 individuals were then sent off to exercise at least one hour a day. After two months, the depression and self-esteem survey was administered again and showed that depression symptoms declined and self-esteem increased. You're a bit skeptical of the results. You believe there are two problems. One, you really know the effects of the treatment without a control group, and two, you suspect there's interviewer bias.
Completely randomized design comparing those who exercise vs. those who don't exercise, and a blind procedure
You're going to test two new varieties of fish food vs. some commonly used fish food. You set up an experiment as follows: 60 fish are randomly assigned to each of three different tanks. One tank is randomly selected to receive one of the new foods, another tank to receive the other new food, and the third tank to receive the common food. Fish growth is measured over time. This is an example of:
a completely randomized design with a control group.
A researcher identifies a sample of teenagers and chooses two males, age 16 years old, from lower-income families. She randomly selects one of the males to be in an intensive tutoring course; she places the second male in a standard classroom. She continues doing this with pairs of males and females. This is an example of:
matching pairs for random assignment on gender, age, and income status.
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