Question 1

You want to investigate whether teenagers in England tend to read more Harry Potter books than teenagers in the United States.
-Identify the explanatory variable, and classify it as categorical or quantitative.

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Question 2

You want to investigate whether teenagers in England tend to read more Harry Potter books than teenagers in the United States.
-Identify the response variable, and classify it as categorical or quantitative.
If you read a report that Hospital A has a higher mortality (death) rate than Hospital B when treating heart attack patients, it's possible that the severity of the patient's condition is a confounding variable.

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Question 3

You want to investigate whether teenagers in England tend to read more Harry Potter books than teenagers in the United States.
-Describe what it means for patient's condition to be a confounding variable in this context. Be sure to indicate how this potential confounding variable could be related both to the explanatory and the response variable.

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Question 4

A university wants to know the average yearly salary of its alumni ten years after graduation. It has a list of all alumni who graduated ten years ago and writes to each one, asking for information about annual salary. Suppose that $40 \%$ of the alumni respond to this invitation.
-Describe (in words) the parameter of interest.

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Question 5

A university wants to know the average yearly salary of its alumni ten years after graduation. It has a list of all alumni who graduated ten years ago and writes to each one, asking for information about annual salary. Suppose that $40 \%$ of the alumni respond to this invitation.
-Describe (in words) the statistic of interest.

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Question 6

A university wants to know the average yearly salary of its alumni ten years after graduation. It has a list of all alumni who graduated ten years ago and writes to each one, asking for information about annual salary. Suppose that $40 \%$ of the alumni respond to this invitation.
-Would you consider the sample to be representative of the population, or is this sampling method biased? Explain.
A national survey of 12- to 17 -year-olds conducted in 2011 found that teens who spend time on a social networking site in a typical day are three times more likely to use alcohol than teens who do not spend time on a social networking site in a typical day. Headlines proclaimed that social networking causes drinking. A blogger responded that this conclusion is not justified and that age is a confounding variable.

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Question 7

A university wants to know the average yearly salary of its alumni ten years after graduation. It has a list of all alumni who graduated ten years ago and writes to each one, asking for information about annual salary. Suppose that $40 \%$ of the alumni respond to this invitation.
-Describe what it means for age to be a confounding variable in this context. Be sure to indicate how this potential confounding variable could be related both to the explanatory and the response variables.

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Question 8

An organization called The Knot Inc. hosts two popular wedding websites and conducted a national (U.S.) survey of nearly 19,000 couples who were married in the year 2010 . The organization reported that the average amount spent on a wedding, excluding honeymoon, was $\$ 26,984$ and that $43 \%$ of the ceremonies were held outdoors.
-Identify the population of interest in this survey.

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