AP Statistics - Designing Studies

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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CCSS.HSS.IC.B.3

Corn variety 1 yielded 140 bushels per acre last year at a research farm. This year, corn variety 2 planted in the same location, yielded only 110 bushels per acre. Unfortunately, we don't know whether the difference is due to the superiority of variety 1 or the effect of this year's drought. This is an example of

• bias

• the placebo effect

• matched pairs design

• replication

• confounding

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CCSS.HSS.IC.B.3

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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CCSS.HSS.IC.B.3

Two essential features of all statistically designed experiments are

• compare several treatments; use the double-blind method

• compare several treatments; use chance to assign subjects to treatments

• always have a placebo group; use the double-blind method

• use a block design; use chance to assign subjects to treatments

• use enough subjects; always have a control group

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CCSS.HSS.IC.B.3

An example of a nonsampling error that can reduce the accuracy of a sample survey is

• using voluntary response to choose the sample

• using the telephone directory as the sampling frame

• interviewing people at shopping malls to obtain a sample

• variation due to chance in choosing a sample at random

• inability to contact many members of the sample

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CCSS.HSS.IC.B.3

Why is replication a good practice in experimental designs?

• It "controls" the effects of known factors.

• It eliminates chance variation.

• It allows for causation to potentially be determined.

• It makes a study random.

• It allows for chance variation to be estimated.

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CCSS.HSS.IC.B.3

What is an example of a non-biased sampling method?

• A teacher selecting only students with the last names starting with the letters P through Z to take a pop quiz.

• A teacher selecting only students with a current A or B grade in the class to take a pop quiz.

• A teacher picking 10 names out of a jar containing the names of all the students in the class to take a pop quiz.

• A teacher selecting only students wearing long sleeves to take a pop quiz.

• A teacher asking the students sitting on the right side of the classroom to take a pop quiz.

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CCSS.7.SP.A.1

CCSS.HSS.IC.A.1

If a study has three factors, each with three levels, how many treatments are there?

• 4

• 5

• 6

• 9

• 27

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CCSS.HSS.IC.B.3

Suzy and John each claim to make the best chicken enchiladas. To test their claims, they each prepare enchiladas and serve them to a random sample of friends. Those friends are then surveyed using the same questionnaire. Results are compared. Which of the following statements about the study is true? (Note: Suzy and John do not have the same friends in common.)

• The results will generalize because the questionnaires were identical.

• The samples were random, so the results should not be biased.

• The results of this study will definitively prove whose enchiladas are better.

• There is a convenience sampling bias present for both Suzy and John.

• The study was a single-blind design study.

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CCSS.HSS.IC.B.3

A school committee member is lobbying for an increase in the gasoline tax to support the county school system. The local newspaper conducted a survey of county residents to assess their support for such an increases. What is the population of interest here?

• All school-aged children

• All county residents

• All county residents with school-aged children

• All county residents with children in the county school system

• All county school system teachers

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CCSS.7.SP.A.1

CCSS.HSS.IC.A.1