AP Statistics Experiments and Surveys Quizizz

You are asked to give a survey and want to make groups. Which one is not appropriate.

• Stratified

• Cluster

• Blocking

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 six times, three times while wearing a floral-scented mask and three times wearing an unscented mask. The three trials for each mask closely followed one another. Testers measured 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 than those wearing the unscented mask, although the difference was not statistically significant. This study is

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

A large company wants to conduct a survey to determine the proportion of its male employees who practice yoga on a daily basis. Two of its regional offices are chosen at random and all of the male employees at each office are surveyed. This plan is an example of which type of sampling?

• Cluster

• Convenience

• Simple Random

• Stratified Random

• Systematic

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Which of the following is a key distinction between well designed experiments and observational studies?

• More subjects are available for experiments than for observational studies.

• Ethical constraints prevent large-scale observational studies.

• Experiments are less costly to conduct than observational studies.

• An experiment can show a direct cause-and-effect relationship, whereas an observational study cannot.

• Tests of significance cannot be used on data collected from an observational study.

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The oil used in gasoline engines for cars can be mineral oil, a synthetic blend (a mixture of mineral oil and synthetic oil), or pure synthetic oil. An experiment is to be conducted to determine whether oil type effects a car's engine. In previous studies, it was determined that engine size (4-cylinder, 6-cylinder, 8-cylinder) is associated with engine life, but car type (coupe, sedan, wagon) is not associated with engine life. This experiment would best be done

• by blocking on car type

• by blocking on oil type

• by blocking on engine life

• by blocking on engine size

• without blocking

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A consumer group for a camping and hiking magazine would like to compare a new mosquito spray made with essential oils to a traditional spray that contains DEET. The group is interested in the amount of time the spray protects the wearer from the bloodthirsty insects. Subjects will be treated and sent into a mosquito filled meadow for a 12-hour period. Which of the following is the BEST method for assigning the treatments?

• Have the subjects choose which spray theu are willing to use for the 12-hour period.

• Assign the sprays to the subjects on the basis of their camping and hiking experience without randomization.

• Give the new spray to all subjects for a 12-hour period, then give the DEET spray to all subjects for a second 12-hour period.

• Randomly assign the subjects to two groups, giving the new spray to one group and the DEET spray to the second group.

• Each subject uses a randomization device to select which spray to apply to the right side of their body. The other spray is then applied to the left side of their body.

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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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To ensure that the experiment results are valid it is important that the experiment be...

• Replicated
• Controlled
• Randomized
• All of the above

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The Community Intervention Trial for Smoking Cessation asked whether a community-wide advertising campaign would reduce smoking. The researchers located 11 pairs of communities, each pair similar in location, size, economic status, and so on. One community in each pair participated in the advertising campaign and the other did no. This is

• an observational study

• a matched pairs experiment

• a completely randomized experiment

• a randomized block design, but not matched pairs

• a stratified random sample

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A double-blind experiment was conducted to evaluate the effectiveness of the Salk polio vaccine. The purpose of keeping the diagnosing physician unaware of the treatment status of the experimental subjects was to

• eliminate grounds for malpractice suits

• ensure that subjects were randomly assigned to treatments

• eliminate a possible source of bias

• make sure nobody is harmed

• avoid the placebo effect

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