Question 1

Which of the following best describes a voluntary response sample?

Accepted Answer

A sample where respondents themselves decide whether to participate.

Question 2

A researcher wants to study the effect of a new drug. She randomly assigns patients to either a treatment group or a placebo group. What is this method called?

Accepted Answer

Randomization

Question 3

Which of the following is an example of quantitative data?

Accepted Answer

The ages (in years) of subjects enrolled in a clinical trial.

Question 4

A casino employee rolls a fair die until the number 5 turns up and counts the number of rolls required. What type of data is this?

Accepted Answer

Discrete data of the infinite type

Question 5

Which of the following statements about correlation is correct?

Accepted Answer

Correlation does not imply causation.

Question 6

A survey includes many missing salary entries because those with very low incomes are reluctant to reveal their salaries. What is the likely effect on the results?

Accepted Answer

The average salary will appear higher than it really is.

Question 7

Which sampling method involves selecting every $$kth $$subject from the population?

Accepted Answer

Systematic sampling

Question 8

What is the correct way to convert 85% to a decimal?

Accepted Answer

Divide 85 by 100: $$85\div100=0.85$$

Question 9

Which of the following is NOT a recommended way to deal with missing data?

Accepted Answer

Ignore missing data if they are missing not at random.

Question 10

A study collects data from a past time period by examining records and interviews. What type of study is this?

Accepted Answer

Retrospective (case-control) study

Question 11

Which level of measurement allows for meaningful differences and ratios, and has a natural zero starting point?

Accepted Answer

Ratio level

Question 12

A researcher divides a population into groups based on similar characteristics, then randomly samples within each group. What sampling method is this?

Accepted Answer

Stratified sampling

Question 13

Which of the following is an example of categorical data?

Accepted Answer

Eye color of subjects enrolled in a clinical trial.

Question 14

A data value is missing completely at random if:

Accepted Answer

The likelihood of its being missing is independent of its value or any other values in the data set.

Question 15

Which of the following is a key principle when dealing with percentages?

Accepted Answer

Replace the % symbol with division by 100, then multiply by the whole value.

Question 16

A study observes and measures specific characteristics but does not attempt to modify the individuals being studied. What type of study is this?

Accepted Answer

Observational study

Question 17

Which of the following is an example of discrete data?

Accepted Answer

The number of physical examinations given during a week.

Question 18

A researcher partitions the population into clusters, randomly selects some clusters, and then selects all members of the selected clusters. What sampling method is this?

Accepted Answer

Cluster sampling

Question 19

Which of the following is a potential problem with using identification numbers (such as 1, 2, 3, ...) as data in statistical calculations?

Accepted Answer

They are categorical data and have no computational significance.

Question 20

A study finds that the likelihood of an event occurring by chance is 3%. What can be said about the statistical significance?

Accepted Answer

Statistical significance is achieved because $$3\% \leq 5\%.$$

Introduction to Statistics: Key Concepts and Methods

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