FiltersDone

Question type

Essay

Multiple Choice

Short Answer

True False

Matching

Exam 7: Designing Experiments

Show Answer

Share

---

All types

Filters

Study FlashcardsPractice ExamLearn

Question 21

Multiple Choice

Review LaterAdd Note

Review Later

Avandia is an antidiabetic drug. In a study of tolerance and side effects of Avandia, 428 patients with prediabetes were given 4 mg of Avandia daily for 26 weeks. The researchers compared the patients' baseline cholesterol levels at the beginning of the study with their level after the 26 weeks of treatment. The results show a significant increase in their low-density lipoprotein (LDL) cholesterol ("bad cholesterol") level. ​ This is an example of

A) a retrospective, case-control observational study.
B) a prospective, cohort observational study.
C) a completely randomized experiment.
D) a matched pairs experiment.

Correct Answer

verified

Show Answer

Question 22

Multiple Choice

Review LaterAdd Note

Review Later

Which of the following does NOT describe a treatment?

A) A specific experimental condition applied to the subjects
B) A combination of specific values of each factor
C) A response variable
D) A placebo

Correct Answer

verified

Show Answer

Question 23

Multiple Choice

Review LaterAdd Note

A study examined the impact of THC (the active ingredient in marijuana) on various physiological and psychological variables. The study recruited a sample of 18 young adults who were habitual marijuana smokers. Participants came to the lab 3 times, each time completing the entire series of tests and questionnaire, but each time smoking a different marijuana cigarette: one with 3.9% THC, one with 1.8% THC, and one with no THC (a placebo) . The order of the conditions was randomized and participants were not told how much THC was in the cigarette they smoked until after all the data were collected. This is an example of

What is the best description of an observed effect so large that it would rarely occur by chance?

Which term applies to any experimental condition applied to the subjects?

Consumer Reports compared the effectiveness of an antiwrinkle cream with that of a plain moisturizer in reducing the appearance of wrinkles. The researchers enrolled 79 subjects with moderate to marked wrinkles, and instructed them to use both products, one on each side of the face, every morning for 12 weeks. The subjects didn't know which products they were using. At the end of the study, panelists examined before and after photos of the subjects to assess wrinkle appearance. The panelists did not know which product the subjects had used. Which of the following statements is TRUE?

A study attempts to determine whether a new medication is effective at lowering blood pressure. Forty subjects with hypertension who volunteer to participate in the study are to be given both the new medication and a placebo. The order in which each subject receives the treatment is randomized, and the subjects do not know which treatment they are getting. Each treatment is administered for four weeks. At the end of each four-week period a subject's blood pressure is recorded. What are the experimental units in this study?

A researcher is interested in investigating the relationship between sugar consumption and weight gain for high school students. Fifteen volunteers were randomly assigned to one of two groups. The first group contained six volunteers who were put on a low-sugar diet. The second group consisted of the remaining nine volunteers, who were put on a diet in which sugar constituted approximately 15% of their calories consumed. After eight weeks, the change in weight was recorded for each of the volunteers. Which of the following principles of experimentation are used in this study?

The drug valproate has been shown in mice to facilitate adult learning of skills typically acquired during early life. A study enrolled healthy adult human males with no advanced musical training and taught them to identify absolute pitch, a rare ability typically learned in early childhood. In a first stage, the participants were randomly assigned to valproate or a placebo. In a second stage, the conditions were reversed, so that a participant who received the placebo first took valproate for the second stage, and vice versa. Which type of study design was used?

Are patches more effective than oral medication in helping individuals stop smoking? Two researchers randomly assigned 22 people to one of the two treatment groups (11 people were assigned to each group) . The subjects were monitored for six weeks, during which they received treatment every day-a new patch for subjects in the first group and a single pill for subjects in the second group. The researchers reported that subjects wearing the patches were less likely to quit smoking, although the difference was not statistically significant. Which type of study is this?

A study recruited 48 overweight adults aged 55 to 75 years, and randomly divided them into two groups. Participants in one group drank 2 cups of water prior to their meals; the other group did not. All participants ate a low-calorie diet during the study. Over the course of 12 weeks, water drinkers lost about 15.5 pounds, while the non-water drinkers lost about 11 pounds, on average. Which type of study is this?

A study recruited 48 overweight adults aged 55 to 75 years, and randomly divided them into two groups. Participants in one group drank 2 cups of water prior to their meals; the other group did not. All participants ate a low-calorie diet during the study. Over the course of 12 weeks, water drinkers lost about 15.5 pounds, while the non-water drinkers lost about 11 pounds, on average. What is the response variable in this study?

A study examined the effect of garlic on blood cholesterol levels. A total of 192 subjects with starting low-density lipoprotein (LDL) cholesterol ("bad cholesterol") levels between 130 and 190 mg/dl were randomly assigned to one of four treatments for six months: raw garlic eaten daily, a powdered garlic supplement taken daily (Garlicin brand) , an aged-garlic extract taken daily (Kyolic brand) , or a placebo pill taken daily. The study found no significant or clinical differences in blood cholesterol levels between the four groups at the end of the study. What were the subjects in the study?

A researcher is interested in investigating the relationship between sugar consumption and weight gain for high school students. Fifteen volunteers were randomly assigned to one of two groups. The first group contained six volunteers who were put on a low-sugar diet. The second group consisted of the remaining nine volunteers, who were put on a diet in which sugar constituted approximately 15% of their calories consumed. After eight weeks, the change in weight was recorded for each of the volunteers. What is the explanatory variable?

A study randomly assigned subjects to receive either St. John's wort extract (n = 98) or a placebo (n = 102) . For each subject, the investigators assessed the person's rate of change in the Hamilton Rating Scale for Depression over the treatment period. Which type of study is this?

The Physicians' Health Study followed 22,000 male physicians for a period of several years. Approximately 11,000 took an aspirin every second day, while the rest took a placebo. At the completion of the study, it was noted whether a subject had experienced a heart attack during the period of the study. It was found that the aspirin group had significantly fewer heart attacks than the placebo group. What is the response variable in this experiment?

A study examined the effect of garlic on blood cholesterol levels. A total of 192 subjects with starting low-density lipoprotein (LDL) cholesterol ("bad cholesterol") levels between 130 and 190 mg/dl were randomly assigned to one of four treatments for six months: raw garlic eaten daily, a powdered garlic supplement taken daily (Garlicin brand) , an aged-garlic extract taken daily (Kyolic brand) , or a placebo pill taken daily. The study found no significant or clinical differences in blood cholesterol levels between the four groups at the end of the study. Which type of study is this?

Ability to grow in shade may help pine trees found in the dry forests of Arizona resist drought. To test this hypothesis, investigators planted pine seedlings in a greenhouse to a randomly assigned light intensity: full light, light reduced to 25% of normal, or light reduced to 5% of normal. At the end of the study, they dried the young trees and weighed them. Which type of study is this?

Noroviruses cause roughly 21 million cases of gastroenteritis ("stomach flu") annually in the United States. A study examined the effectiveness of a new norovirus vaccine. Healthy adult volunteers received, at random, either the vaccine or a placebo. They were then exposed to the norovirus. In all, 14 of the 38 vaccinated subjects suffered from gastroenteritis, compared with 27 of the 39 subjects who received a placebo. Which type of study is this?

An excellent experimental design guarantees that any difference between two groups is entirely due to differences in the treatments applied.