1. Intro to Stats and Collecting Data

Determine whether the statement is true or false. If it is false, rewrite it as a true statement.

A double-blind experiment is used to increase the placebo effect.

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

A research study compared the memory retention of subjects when a learning activity was followed by a brief period of wakeful rest and when a learning activity was followed by a brief period of distraction. (Source: Springer Nature)

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

A study used periodic blood pressure readings and brain MRIs of adults to find that adults with long periods of high blood pressure were more likely to develop cerebral small blood vessel disease. (Source: American Heart Association)

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.

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.

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?

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

How does the media influence the opinions of voters?

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

How much do you exercise during an average week?

In Exercises 9 and 10, determine whether the study is an observational study or an experiment. Explain.

To study the effect of using digital devices in the classroom on exam performance, researchers divided 726 undergraduate students into three groups, including a group that was allowed to use digital devices, a group that had restricted access to tablets, and a control group that was “technologyfree.” (Source: Massachusetts Institute of Technology)

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

Researchers conduct a study to determine whether cataract surgery patients experience different comfort levels during their first and second surgeries. Researchers based their results on a verbal questionnaire. (Source: Medicine)

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?

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 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)