AP Stats Unit 1 Review

A farmer is conducting an experiment to determine which variety of apple tree, Fuji or Gala, will produce more fruit in his orchard. The orchard is divided into 20 equally sized square plots. He has 10 trees of each variety and randomly assigns each tree to a separate plot in the orchard. What are the experimental unit(s) in the study?

• The trees

• The plots

• The apples

• The farmer

• The orchard

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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A human experimental unit. (participant)

• Subject
• Case
• Identifier Variable
• Variable

A variable in which the numbers act as numerical values (always has units).

• Quantitative Variable
• Categorical Variable
• Identifier Variable
• Nominal Variable

In an experiment, who are the "subjects"?

• The people conducting the experiment. 
• The individuals taking part in the experiment. 
• The topic of the experiment. 
• The people funding the experiment. 

Medical experiments, such as one to compare aspirin with a placebo for preventing heart attacks, are often double blind. This means that...

• neither the subject nor the doctors know which treatment the patient received. 
• subjects choose which treatment they get, but do not tell the doctors. 
• all individual data are kept confidential. 
• subjects are told either their treatment or their medical condition. 

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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 to the effect of this year's drought. This is an example of...

• random sampling error. 
• nonsampling error.
• confounding. 
• the placebo effect. 

The most important advantage of experiments over observational studies is that...

• experiments are usually easier to carry out than observational studies. 
• experiments can give better evidence of causation. 
• confounding cannot happen in experiments. 
• an observational study cannot have a response variable. 

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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.

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To gather information about the validity of a new standardized test for 10-grade students in a particular state, a random sample of 15 high schools was selected from the state. The new test was administered to every 10 grade student in the selected high schools. What kind of sample is this?

• SRS

• Stratified

• Cluster

• Systematic

• Voluntary response

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