Study Design Review Game

Can pleasant aromas help a student learn better? Two researchers believed that the presence of a floral scent could improve a person's learning ability in certain situations. They had 22 people work through a pencil-and-paper maze 6 times. Three of the times they wore a floral-scented mask and three times they wore an unscented mask. The three trials for each mask followed one another. Testers measures the length of time it took subjects to complete each of the six trials. They reported that, on average, subjects wearing the floral-scented mask completed the maze more quickly that those wearing the unscented mask, although, the difference was not statistically significant. This study is:

• a convenience sample
• an oberservational study
• an experiment, but not double-blind
• a double-blind experiment

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CCSS.HSS.IC.B.3

CCSS.HSS.IC.B.5

A television station is interested in predicting whether voters in its viewing area are in favor of federal funding for health care. It asks its viewers to phone in and indicate whether they support or are opposed to this. Of the 2241 viewers who phoned in, 1574 were opposed to federal funding for healthcare.
Referring to the information above, the viewers who phoned in are

• a voluntary response sample
• a convenience sample
• a census
• a population

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CCSS.HSS.IC.B.3

A marketing research firm wished to determine if the adult men in Laramie, Wyoming, would be interested in a new upscale men's clothing store. From a list of all residential addresses in Laramie, the first selects a simple random sample of 100 and mails a brief questionnaire to each. The population of interest is

• all adult men in Laramie, WY
• all residential addresses in Laramie, WY
• the members of the marking firm conducting the survey
• the 100 addresses to which the survey was mailed

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CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.3

A researcher is interested in the cholesterol levels of adults in the city in which she lives. A free cholesterol screening program is set up in the downtown area during the lunch hour. Individuals can walk in and have their cholesterol levels determined for free. One hundred and seventy three people use the service, and their average cholesterol is 217.8. The sample obtained is an example of

• a simple random sample, since the experimenter did not know beforehand which individuals would come to the screening.
• a stratified sample of high and low cholesterol individuals
• a sample probably containing bias and undercoverage.
• a multistage sample of varying cholesterol levels.

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CCSS.7.SP.A.1

CCSS.HSS.IC.A.1

A study of human development showed two 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 the different kinds of movies. One kind of movie was shown at 8 AM (right after the children had breakfast) and another at 11 AM (right before the children had lunch). It was found that during the movie shown at 11 AM, more crackers were eaten than during the movie shown at 8 AM. The investigators concluded that the different types of movies had an effect on appetite.
The results cannot be trusted because

• the study was not double-blind. Neither the investigators nor the children should have been aware of which movie was being shown.
• the investigators were biased. They knew beforehand what they hoped the study would show.
• the investigators should have used several bowls, with crackers randomly placed in each.
• the time the movie was shown is a confounding variable.

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CCSS.HSS.IC.B.3

CCSS.HSS.IC.B.5

The web portal AOL places opinion poll questions next to many of its news stories. Simply click your response to join the sample. One of the questions in January 2008 was "Do you plan to diet this year?" More than 30,000 people responded, with 68% saying "Yes." You conclude that

• about 68% of Americans planned to diet in 2008

• the poll used a convenience sample, so the results tell us little about the population of all adults.

• the poll uses voluntary response, so the results tell us little about the population of all adults.

• the sample is too small to draw any conclusions.

Your statistics class has 30 students. You want to call an SRS of 5 students from your class to ask where they use a computer for the online quizzes. You label the student 01, 02, ..., 30. You enter the table of random digits at this line:

14459 26056 31424 80371 65103 62253 22490 61181

Your SRS contains the students listed:

• 14,45,92,60,56

• 14,31,03,10,22

• 14,03,10,22,22

• 14,03,10,22,06

• 14,03,10,22,11

A gardener wants to try different combinations of fertilizer (none, 1 cup, 2 cups) and mulch (none, wood chips, pine needles, plastic) to determine which combination produces the highest yield for a variety of green beans. He has 60 green bean plants to use in the experiment. If he wants an equal number of plants to be assigned to each treatment, how many plants will be assigned to each treatment?

• 1

• 3

• 4

• 5

• 12

An SRS of 1200 adult Americans is selected and each person is asked the following question: "In light of the huge national deficit should the government at this time spend additional money to establish a national system of health insurance?" Only 39% of those responding answered "Yes." This survey

• is reasonably accurate since it used a large SRS.

• needs to be larger since only about 24 people were drawn from each state.

• probably understates the percent of people who favor a system of national health insurance.

• is very inaccurate but neither understates nor overstates the percent of people who favor a system of national health insurance. Because an SRS was used, the survey is unbiased.

• probably overstates the percent of people who favor a system of national health insurance.

Researchers randomly selected 1700 people from Canada who had never suffered a heart attack and rated the happiness of each person. Ten years later, the researchers followed up with each person and found that people who were initially rated as happy were less likely to have a heart problem. Which of the following is the most appropriate conclusion based on this study?

• Happiness causes better heart health for all people

• Happiness causes better heart health for Canadians

• Happiness causes better heart health for the 1700 people in the study

• Happier people in Canada are less likely to have heart problems

• Happier people in the study were less likely to have heart problems