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STATISTICS: INFORMED DECISIONS USING DATA QUESTIONS
WITH VERIFIED ANSWERS DETAILED RATIONALES GRADED A+
SECTION 1: DATA COLLECTION & STUDY DESIGN (Questions 1–25)
Question 1.
Which of the following best describes an observational study?
A) The researcher assigns treatments to subjects.
B) The researcher observes and measures characteristics without manipulating any variable.
C) The researcher uses random assignment to create groups.
D) The researcher controls all variables.
Correct Answer: B
Rationale: In an observational study, the researcher observes and measures characteristics
without manipulating the subjects or assigning treatments.
Question 2.
A researcher randomly selects 50 students from each grade level in a high school. What
sampling method is used?
A) Simple random sample
B) Stratified sample
C) Cluster sample
D) Systematic sample
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Correct Answer: B
Rationale: Stratified sampling divides the population into subgroups (strata) and randomly
samples from each stratum.
Question 3.
Which type of bias occurs when individuals who choose to respond to a survey differ from
those who do not respond?
A) Sampling bias
B) Nonresponse bias
C) Response bias
D) Measurement bias
Correct Answer: B
Rationale: Nonresponse bias occurs when those who do not respond differ systematically from
those who do respond.
Question 4.
A study finds that ice cream sales and drowning deaths are positively correlated. What is the
most likely explanation?
A) Ice cream causes drowning.
B) Drowning causes ice cream sales.
C) Both are influenced by a lurking variable, such as temperature.
D) The correlation is due to chance.
Correct Answer: C
Rationale: A lurking variable (temperature) influences both ice cream sales and drowning
deaths, creating a spurious correlation.
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Question 5.
Which of the following is a quantitative variable?
A) Eye color
B) Gender
C) Height
D) Zip code
Correct Answer: C
Rationale: Height is a quantitative variable because it is numerical and measurable. Eye color,
gender, and zip code are qualitative.
Question 6.
A researcher selects every 10th name from a list. What sampling method is used?
A) Simple random sample
B) Stratified sample
C) Cluster sample
D) Systematic sample
Correct Answer: D
Rationale: Systematic sampling selects every kth individual from a list after a random start.
Question 7.
Which of the following is an example of a nominal level of measurement?
A) Temperature in Fahrenheit
B) Ranking of runners
C) Types of cars
D) Weight in pounds
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Correct Answer: C
Rationale: Nominal data are categories with no inherent order. Types of cars are nominal.
Question 8.
In an experiment, the variable that is manipulated is called the:
A) Dependent variable
B) Independent variable
C) Confounding variable
D) Response variable
Correct Answer: B
Rationale: The independent variable is manipulated by the researcher to observe its effect on
the dependent variable.
Question 9.
Which of the following is a voluntary response sample?
A) A random digit dialing poll
B) A survey where viewers call in to vote
C) A stratified random sample
D) A cluster sample
Correct Answer: B
Rationale: A voluntary response sample consists of individuals who choose to participate, often
leading to bias.
Question 10.
A placebo is used in an experiment to:
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STATISTICS: INFORMED DECISIONS USING DATA QUESTIONS
WITH VERIFIED ANSWERS DETAILED RATIONALES GRADED A+
SECTION 1: DATA COLLECTION & STUDY DESIGN (Questions 1–25)
Question 1.
Which of the following best describes an observational study?
A) The researcher assigns treatments to subjects.
B) The researcher observes and measures characteristics without manipulating any variable.
C) The researcher uses random assignment to create groups.
D) The researcher controls all variables.
Correct Answer: B
Rationale: In an observational study, the researcher observes and measures characteristics
without manipulating the subjects or assigning treatments.
Question 2.
A researcher randomly selects 50 students from each grade level in a high school. What
sampling method is used?
A) Simple random sample
B) Stratified sample
C) Cluster sample
D) Systematic sample
1|Page
,Page 2 of 92
Correct Answer: B
Rationale: Stratified sampling divides the population into subgroups (strata) and randomly
samples from each stratum.
Question 3.
Which type of bias occurs when individuals who choose to respond to a survey differ from
those who do not respond?
A) Sampling bias
B) Nonresponse bias
C) Response bias
D) Measurement bias
Correct Answer: B
Rationale: Nonresponse bias occurs when those who do not respond differ systematically from
those who do respond.
Question 4.
A study finds that ice cream sales and drowning deaths are positively correlated. What is the
most likely explanation?
A) Ice cream causes drowning.
B) Drowning causes ice cream sales.
C) Both are influenced by a lurking variable, such as temperature.
D) The correlation is due to chance.
Correct Answer: C
Rationale: A lurking variable (temperature) influences both ice cream sales and drowning
deaths, creating a spurious correlation.
2|Page
,Page 3 of 92
Question 5.
Which of the following is a quantitative variable?
A) Eye color
B) Gender
C) Height
D) Zip code
Correct Answer: C
Rationale: Height is a quantitative variable because it is numerical and measurable. Eye color,
gender, and zip code are qualitative.
Question 6.
A researcher selects every 10th name from a list. What sampling method is used?
A) Simple random sample
B) Stratified sample
C) Cluster sample
D) Systematic sample
Correct Answer: D
Rationale: Systematic sampling selects every kth individual from a list after a random start.
Question 7.
Which of the following is an example of a nominal level of measurement?
A) Temperature in Fahrenheit
B) Ranking of runners
C) Types of cars
D) Weight in pounds
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, Page 4 of 92
Correct Answer: C
Rationale: Nominal data are categories with no inherent order. Types of cars are nominal.
Question 8.
In an experiment, the variable that is manipulated is called the:
A) Dependent variable
B) Independent variable
C) Confounding variable
D) Response variable
Correct Answer: B
Rationale: The independent variable is manipulated by the researcher to observe its effect on
the dependent variable.
Question 9.
Which of the following is a voluntary response sample?
A) A random digit dialing poll
B) A survey where viewers call in to vote
C) A stratified random sample
D) A cluster sample
Correct Answer: B
Rationale: A voluntary response sample consists of individuals who choose to participate, often
leading to bias.
Question 10.
A placebo is used in an experiment to:
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