Which technique used in Exercise 7 could lead to a biased study? Explain.

Determine the level of measurement of the data set. Explain your reasoning.

The horsepowers of racing car engines

An experiment is performed to test the effects of a new drug on attention-deficit/hyperactivity disorder (ADHD). The experimenter identifies 320 people ages 7 to 44 with ADHD to participate in the experiment. The subjects are divided into equal groups according to age. Within each group, subjects are then randomly selected to be in either the treatment group or the control group. What type of experimental design is being used for this experiment?

Identify the population and the sample. Describe the sample data set.

Eighty-three doctors working in the St. Louis area were surveyed concerning their opinions on health care reform.

Determine whether the data are qualitative or quantitative. Explain your reasoning.

The marital statuses of the employees of a casino

Determine whether the data are qualitative or quantitative. Explain your reasoning.

The zip codes of a sample of 200 customers at a sporting goods store

Determine the level of measurement of the data set. Explain.

The total compensations (in millions of dollars) of the ten highest-paid CEOs at U.S. public companies are listed. (Source: 24/7 Wall St.)

280.6 66.9 42.9 36.5 34.3 31.6 31.6 28.8 26.4 25.8

Which part of the survey described in Exercise 3 represents the descriptive branch of statistics? Make an inference based on the results of the survey.

Determine whether the number describes a population parameter or a sample statistic. Explain your reasoning.

In a survey of 1000 household food purchasers, 24.7% say that they avoid meat, dairy, and eggs produced by animals living in confined conditions. (Source: FoodPrint)

Determine whether each number describes a population parameter or a sample statistic. Explain.

In a recent year, the average evidence-based reading and writing score on the SAT was 528. (Source: College Board)

Determine whether the survey question is biased. If the question is biased, suggest a better wording.

How many hours of sleep do you get on a normal night?

Determine whether the survey question is biased. If the question is biased, suggest a better wording.

Do you agree that the town’s ban on skateboarding in parks is unfair?

Determine whether the data are qualitative or quantitative, and determine the level of measurement of the data set. Explain your reasoning.

The numbers of employees at fast-food restaurants in a city are listed.

20 11 6 31 17 23 12 18 40 22 13 8 18 14 37 32 25 27 25 18

Identify the sampling technique used, and discuss potential sources of bias (if any). Explain.

Questioning teachers as they leave a faculty lounge, a researcher asks 45 of them about their teaching styles.

Researchers in Japan tested the effect of cannabidiol (CBD) in treating late teenagers with social anxiety disorder (SAD). Thirty-seven 18- to 19-year-old teenagers with SAD took part in the study. The patients were assigned at random to receive a daily dose of either CBD or a placebo for 4 weeks. Symptoms were measured using The Fear of Negative Evaluation Questionnaire and the Liebowitz Social Anxiety Scale at the beginning and end of the treatment. (Source: Frontiers in Psychology)

a. Identify the experimental units and treatments used in this experiment.

A company wants to test the effectiveness of a new acne cream. The company recruits 500 girls ages 13 to 17 who have acne. The subjects are randomly assigned into two groups. One group is given the acne cream and the other is given a placebo that looks exactly like the acne cream. Both groups apply the cream daily for two months. Facial photos are taken at the beginning and end of the treatment to compare results.

Identify the experimental units and treatments used in this experiment.

"Researchers in Japan tested the effect of cannabidiol (CBD) in treating late teenagers with social anxiety disorder (SAD). Thirty-seven 18- to 19-year-old teenagers with SAD took part in the study. The patients were assigned at random to receive a daily dose of either CBD or a placebo for 4 weeks. Symptoms were measured using The Fear of Negative Evaluation Questionnaire and the Liebowitz Social Anxiety Scale at the beginning and end of the treatment. (Source: Frontiers in Psychology)

Identify a potential problem with the experimental design being used and suggest a way to improve it."

A company wants to test the effectiveness of a new acne cream. The company recruits 500 girls ages 13 to 17 who have acne. The subjects are randomly assigned into two groups. One group is given the acne cream and the other is given a placebo that looks exactly like the acne cream. Both groups apply the cream daily for two months. Facial photos are taken at the beginning and end of the treatment to compare results.

b. Identify a potential problem with the experimental design being used and suggest a way to improve it.

"Researchers in Japan tested the effect of cannabidiol (CBD) in treating late teenagers with social anxiety disorder (SAD). Thirty-seven 18- to 19-year-old teenagers with SAD took part in the study. The patients were assigned at random to receive a daily dose of either CBD or a placebo for 4 weeks. Symptoms were measured using The Fear of Negative Evaluation Questionnaire and the Liebowitz Social Anxiety Scale at the beginning and end of the treatment. (Source: Frontiers in Psychology)

The experiment is described as a placebo-controlled, double-blind study. Explain what this means."

A company wants to test the effectiveness of a new acne cream. The company recruits 500 girls ages 13 to 17 who have acne. The subjects are randomly assigned into two groups. One group is given the acne cream and the other is given a placebo that looks exactly like the acne cream. Both groups apply the cream daily for two months. Facial photos are taken at the beginning and end of the treatment to compare results.

c. How could this experiment be designed to be double-blind?

"Researchers in Japan tested the effect of cannabidiol (CBD) in treating late teenagers with social anxiety disorder (SAD). Thirty-seven 18- to 19-year-old teenagers with SAD took part in the study. The patients were assigned at random to receive a daily dose of either CBD or a placebo for 4 weeks. Symptoms were measured using The Fear of Negative Evaluation Questionnaire and the Liebowitz Social Anxiety Scale at the beginning and end of the treatment. (Source: Frontiers in Psychology)

How could blocking be used in designing this experiment?"

Identify the sampling technique used, and discuss potential sources of bias (if any). Explain.

A student asks 18 friends to participate in a psychology experiment.

200 students volunteer for an experiment to test the effects of sleep deprivation on memory recall. The students will be placed in one of five different treatment groups, including the control group.

Explain how you could design an experiment so that it uses a randomized block design.

Determine whether the study is an observational study or an experiment. Explain.

Researchers conduct a study to determine whether a medication based on fish oil known as omega-3 carboxylic acids is effective in reducing the risk of cardiac events in people already at risk. In the study, 13,078 patients are randomly chosen to receive either omega-3 carboxylic acids or a placebo of corn oil daily. Researchers compare the number of cardiac events of the two groups over similar follow-up periods of time. (Source: American Heart Association)

200 students volunteer for an experiment to test the effects of sleep deprivation on memory recall. The students will be placed in one of five different treatment groups, including the control group.

Explain how you could design an experiment so that it uses a completely randomized design.

You want to know the favorite spring break destination among 15,000 students at a university. Determine whether you would take a census or use a sampling. If you would use a sampling, determine which sampling technique you would use. Explain your reasoning.

Identify the sampling technique used, and discuss potential sources of bias (if any). Explain.

Law enforcement officials stop and check the driver of every third vehicle for blood alcohol content.