Final Review Day 2

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Final ReviewDay 2
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Create a Quiz!

• Sample vs. Population
• Response/Explanatory Variable
• Positive/Negative Correlation
• Weak vs. Strong Correlation Coefficient
• y a bx (positive vs. negative slope)

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Explanatory/Response

• Suppose you were to collect data for a pair of
  given variables in order to make a scatterplot.
  For the variables cloudy days and rainy days,
  which is more naturally the response variable and
  which the explanatory variable?

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Explanatory/Response

• Suppose you were to collect data for a pair of
  given variables in order to make a scatterplot.
  For the variables time spent on homework and exam
  grades, which is more naturally the response
  variable and which the explanatory variable?

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Proportions

• The partially completed conditional proportion
  table gives the relative frequencies of the data
  on age (in years) and sex for the residents of a
  retirement home. What percentage of the residents
  are males over 79?

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Proportions

• The partially completed conditional proportion
  table gives the relative frequencies of the data
  on age (in years) and sex for the residents of a
  retirement home. What percentage of the residents
  are females in the age group 70 - 79?

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Complete the Table
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Correlation positive, negative
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Correlation positive, negative
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Correlation positive, negative
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Correlation strongest?
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True or False?

• The closer r is to 0, the weaker the linear
  association between the variables.

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True or False?

• The value of the  correlation 
  is always  between 0 and 1.

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Find the equation of the line of best fit in your
calculator
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True or False?

• Association implies causation.

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• A survey of adults revealed a positive
  correlation between the height of the subject and
  their income in the previous year.
• Explain how gender could be a potential lurking
  variable that could be responsible for the
  association.

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How many males were asked?
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Positive or Negative Slope?

• y 209.9 25.5x

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If r is 0.67

• Is this strong or weak?
• What is the percent of variation?

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y 1.27 0.475x

• If y 50.15 when x 45.1, what is the residual?

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A drug company needs to test a new drug.
Participants in an experiment are randomly given
either the drug or a placebo. If the experiment
is conducted double-blind, then

• The participants are blindfolded when they take
  the drug or placebo.
• The participants do not know whether they are
  taking the drug or a placebo.
• Neither the participants nor the drug company
  executives know which volunteers are taking the
  drug and which the placebo.
• Neither the participants nor the evaluators know
  which volunteers are taking the drug and which
  the placebo.

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A survey is mailed to 1000 voters randomly
selected from a county's registered voters asking
"Do you support a constitutional amendment to ban
abortion?" 235 are returned, and of these 180
respond "yes."

• Whats the biggest source of bias?

23
A magazine publisher mails a survey to every
subscriber asking about the quality of its
subscription service. From which of the following
is this study most likely to suffer?

• A)Undercoverage
• B) Nonresponse bias
• C) Sampling bias
• D) Both nonresponse bias and undercoverage
• E) Both undercoverage and sampling bias

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Our class is numbered from 1 to 30. Who are the
first three numbers to be chosen according to
this random number table?

• 36574 47386 09127 55647

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Our class is numbered from 1 to 500. Who are the
first three numbers to be chosen according to
this random number table?

• 36574 47382 09627 45697

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Retrospective or Prospective

• A study found that nearly 90 of all child
  patients with asthma developed pneumonia in their
  teens.
• A study found that nearly 90 of teens with
  pneumonia had asthma as a child.

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What is the sampling frame?

• I am going to do a survey of patients in a nearby
  hospital.
• I want to ask OConnor students their opinion on
  off campus lunches.
• I want to ask Arizona residents their opinion on
  gun laws.

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What is a placebo?