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Exam 8: Producing Data- Experiments

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Question 21

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In a study of human development, investigators showed two different types of movies to groups of children. Crackers were available in a bowl, and the investigators compared the number of crackers eaten by children watching both movies. One type of movie was shown at 8 A.M. (right after the children had breakfast) and the other type of movie was shown at 11 A.M. (right before the children were to have lunch) . It was found that more crackers were eaten during the movie shown at 11 A.M. than during the movie shown at 8 A.M. The investigators concluded that the different types of movies had different effects on appetite. The results cannot be trusted because:

A) the study was not double blind-neither the investigators nor the children should have been aware of which type of movie was being shown.
B) the investigators were biased-they knew beforehand what the study would show.
C) the investigators should have used several bowls, with crackers randomly placed in each.
D) the time each movie was shown is a confounding variable.

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Question 22

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One hundred sixty people who suffer from painful diabetic neuropathy have volunteered to participate in a study. Eighty are selected at random and are given the drug gabapentin, which (although originally intended to prevent epileptic seizures) has properties that may make it useful to alleviate neuropathy. The remaining participants are given a placebo. A neurologist evaluates the symptoms of all volunteers after two months to determine if there has been substantial improvement in the severity of the symptoms. This study would be double-blind if:

A) neither drug had any identifying marks on it.
B) neither the volunteers nor the neurologist were allowed to see each other during the session in which the neurologist evaluated the severity of the symptoms.
C) neither the volunteers nor the neurologist knew which subjects had received the drug and which had received the placebo.
D) All of the answer options are correct.

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Question 23

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A veterinarian interested in studying the causes of enteroliths in horses suspects that a diet high in alfalfa may be a cause. The veterinarian decides to use the following design: identify 30 horses at high risk for enteroliths, and divide them into 10 groups of 3 horses. Some groups consist of horses in barn stalls, some groups consist of horses in outdoor paddocks, and some groups consist of horses in pastures. Within each group, one horse is randomly assigned to an alfalfa diet, one is assigned to a grass hay diet, and one horse is fed oat hay. When a horse is in a pasture, all the other horses in that pasture will also receive the diet of the study horse. Therefore, only one horse could be selected from a given pasture. The blocking is done:

An educator wishes to study the effects of sleep deprivation on the ability to concentrate. He decides to study the students in a calculus class. Before the start of the class, each student is asked about the number of hours slept the previous night. Each student's eye movement is then tracked throughout the lecture. The amount of time is recorded whenever the student is not focused on either the instructor or taking notes. The class is held at 11 A.M. and the instructor also asks questions about prior classes that day. The response variable is:

A nutritionist has designed an intervention to motivate parents of preschool children to provide more fruits and vegetables to their children. To study the effectiveness of this intervention, the nutritionist will conduct an experiment in which half of the selected study participants will receive the intervention and the others will not. Study subjects will be recruited from families with children who receive medical care for their children through the university health center. The nutritionist will compare the amount of fruit consumed per day by the children in families who received the intervention and by those who did not. Which of the following is true?

Researchers have noted that children who learn to play a musical instrument through taking lessons have higher average SAT scores, higher average GPAs, and higher average class ranks. The various measures of academic success described are examples of:

In order to investigate treatments for morbid obesity, obese subjects satisfying fairly strict requirements were randomly assigned to one of three treatment groups: (1) gastric bypass surgery, (2) participation in a diet and exercise program, or (3) both gastric bypass surgery and participation in a diet and exercise program. Researchers observed the amount of weight lost five years after the study began. This study uses the principles of:

Randomly assigning all subjects to treatment groups is called:

An educator wishes to study the effects of sleep deprivation on the ability to concentrate. He decides to study the students in a calculus class. After consultation with a statistician, the educator decides to randomly allocate students to either a group that will sleep for 8 hours the night before class or 6 hours. The educator does not know which group a student belongs to when she or he comes to class. This study is:

A researcher studying the effect of price cuts on consumers' expectations makes up two different histories of the store price of a hypothetical brand of laundry detergent for the past year. Eight students in a business class view one or the other price history on a computer. Some students see a steady price, whereas others see regular sales that temporarily cut the price. Students are asked the price they would expect to pay. The response is:

A placebo is an important element of many clinical trials because:

To investigate whether women are more likely than men to prefer Democratic candidates, a political scientist selects a large sample of registered voters, both men and women. She asks every voter whether they voted for the Republican or the Democratic candidate in the last election. This is:

A researcher finds 1000 mildly overweight women who exercise regularly, have not had a heart attack, and are willing to participate in the study. She randomly assigns 500 of the women to take an appetite suppressant. The other 500 women are given a placebo. Both groups are followed for five years, and the amount of weight lost after this time is recorded. The response variable in this experiment is:

A study attempts to compare two sunscreens. Each of 50 subjects with varying skin complexions will use both sunscreens-Screen A on one side of the body and Screen B on the other side. For each subject, a coin is tossed to determine which side receives Screen A and which receives Screen B. Researchers measure the amount of ultraviolet light exposure over both treated areas for each subject. This is an example of:

In order to investigate treatments for morbid obesity, obese subjects satisfying fairly strict requirements were randomly assigned to one of three treatment groups: (1) gastric bypass surgery, (2) participation in a diet and exercise program, or (3) both gastric bypass surgery and participation in a diet and exercise program. Researchers observed the amount of weight lost five years after the study began. This study has:

Some researchers have noted that adolescents who spend a lot of time playing video or computer games are at greater risk for depression and violence. This is an example of:

A researcher studying the effect of price cuts on consumers' expectations makes up two different histories of the store price of a hypothetical brand of laundry detergent for the past year. Eight students in a business class view one or the other price history on a computer. Some students see a steady price, whereas others see regular sales that temporarily cut the price. Students are asked the price they would expect to pay. This is an example of:

A veterinarian interested in studying the causes of enteroliths in horses suspects that a diet high in alfalfa may be a cause. The veterinarian decides to use the following design: identify 30 horses at high risk for enteroliths, and divide them into 10 groups of 3 horses. Some groups consist of horses in barn stalls, some groups consist of horses in outdoor paddocks, and some groups consist of horses in pastures. Within each group, one horse is randomly assigned to an alfalfa diet, one is assigned to a grass hay diet, and one horse is fed oat hay. When a horse is in a pasture, all the other horses in that pasture will also receive the diet of the study horse. Therefore, only one horse could be selected from a given pasture. This study has:

Will a fluoride mouthwash used after brushing reduce cavities? Twenty sets of twins were used to investigate this question. One member of each set of twins used the mouthwash after brushing, and the other did not. After six months, the difference in the number of cavities for those using the mouthwash was compared with the number of cavities for those who did not use the mouthwash. This experiment uses:

A veterinarian is interested in studying the causes of enteroliths (stones that form in the gut of horses) . An observational study comparing the diet of horses admitted to the veterinary hospital with enteroliths and the diet of horses admitted for other reasons does not allow causal conclusions to be drawn because: