Question 1

Which of the following best describes the main goal of statistics?

Accepted Answer

To describe and understand sources of variability in data and provide a measure of confidence in conclusions.

Question 2

A researcher wants to estimate the average number of hours college students sleep per night. She surveys 200 students from her university. In this context, what is the sample?

Accepted Answer

The 200 students surveyed.

Question 3

Which of the following is an example of a parameter?

Accepted Answer

The percentage of all registered voters in a country who voted in the last election.

Question 4

Suppose a study reports that 46% of a sample of 100 students own a car. What type of value is 46% in this context?

Accepted Answer

A statistic, because it summarizes the sample.

Question 5

Which of the following variables is qualitative?

Accepted Answer

Gender (male, female, non-binary).

Question 6

A variable is measured as the number of cars passing through a toll booth between 8:00 a.m. and 9:00 a.m. What type of variable is this?

Accepted Answer

Quantitative and discrete.

Question 7

Which of the following is an example of a variable measured at the ordinal level?

Accepted Answer

Letter grades in a class (A, B, C, D, F).

Question 8

Which of the following statements about the interval level of measurement is correct?

Accepted Answer

Differences between values have meaning, but zero does not indicate absence.

Question 9

A researcher wants to study the effect of a new medication on blood pressure. She randomly assigns patients to receive either the medication or a placebo and measures their blood pressure after 8 weeks. What type of study is this?

Accepted Answer

Designed experiment.

Question 10

Which of the following best describes a lurking variable?

Accepted Answer

A variable not considered in a study that affects the response variable.

Question 11

Which sampling method involves dividing the population into non-overlapping groups and then taking a simple random sample from each group?

Accepted Answer

Stratified sampling.

Question 12

A supermarket manager wants to survey every 10th customer who enters the store. What type of sampling method is this?

Accepted Answer

Systematic sampling.

Question 13

Which of the following is a source of sampling bias?

Accepted Answer

Selecting individuals who are easiest to reach.

Question 14

A survey is sent to 1,000 people, but only 200 respond. The opinions of those who did not respond differ from those who did. What type of bias is present?

Accepted Answer

Nonresponse bias.

Question 15

In a double-blind experiment, who is unaware of the treatment assignments?

Accepted Answer

Both the experimental units and the researchers in contact with them.

Question 16

Which of the following best describes a completely randomized design?

Accepted Answer

Each experimental unit is randomly assigned to a treatment.

Question 17

A matched-pairs design is most appropriate when:

Accepted Answer

Experimental units can be paired based on a relevant characteristic.

Question 18

Which of the following is a key difference between stratified and cluster sampling?

Accepted Answer

Stratified sampling divides the population into homogeneous groups and samples from each, while cluster sampling divides into groups and samples all individuals from selected groups.

Question 19

A researcher collects data on the number of hours students study per week and their final exam scores. She wants to determine if there is a relationship between these two variables. What is the explanatory variable?

Accepted Answer

Number of hours studied per week.

Question 20

Which of the following formulas correctly represents the calculation of the sample mean $\bar{x}$ for a sample of $n$ observations $x_1, x_2, ..., x_n$?

Accepted Answer

$\bar{x} = \frac{\sum_{i=1}^{n} x_i}{n}$

Fundamentals of Statistics: Data Collection and Statistical Thinking

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