Question 1

Which of the following best describes the difference between a parameter and a statistic?

Accepted Answer

A parameter is a numerical summary of a population, while a statistic is a numerical summary of a sample.

Question 2

A researcher wants to study the effect of a new drug on blood pressure. She randomly assigns 100 patients to either receive the drug or a placebo and measures their blood pressure after 6 weeks. What type of study is this?

Accepted Answer

Designed experiment

Question 3

Which of the following is an example of a discrete variable?

Accepted Answer

The number of students present in a lecture

Question 4

In a study investigating the relationship between hours spent studying and exam scores, which is the explanatory variable?

Accepted Answer

Hours spent studying

Question 5

A quality-control manager selects every 10th item produced on an assembly line for inspection. Which sampling method is being used?

Accepted Answer

Systematic sampling

Question 6

Which of the following statements about observational studies is TRUE?

Accepted Answer

Observational studies allow researchers to claim association but not causation.

Question 7

A radio station asks listeners to call in and share their opinions about a new music policy. What type of sampling is this?

Accepted Answer

Convenience sampling

Question 8

Which of the following best illustrates response bias?

Accepted Answer

A survey question is worded in a way that leads respondents to answer in a particular way.

Question 9

Suppose a researcher divides a population of students into groups based on their major and then randomly selects students from each group. What sampling method is being used?

Accepted Answer

Stratified sampling

Question 10

Which of the following is a continuous variable?

Accepted Answer

The height of a plant measured in centimeters

Question 11

A researcher wants to estimate the average commute time for employees at a large company. She randomly selects 5 departments and surveys all employees in those departments. What sampling method is this?

Accepted Answer

Cluster sampling

Question 12

Which of the following is an example of sampling bias?

Accepted Answer

A researcher selects only students from morning classes to represent all students.

Question 13

In a double-blind experiment, who is unaware of which treatment is being administered?

Accepted Answer

Both the subject and the researcher in contact with the subject

Question 14

Which of the following best describes the placebo effect?

Accepted Answer

A phenomenon where a person experiences improvement after receiving a treatment with no therapeutic effect

Question 15

A researcher wants to study the effect of exercise on cholesterol levels. She randomly assigns participants to three groups: no exercise, moderate exercise, and intense exercise. After 12 weeks, she measures their cholesterol levels. What is the response variable?

Accepted Answer

Cholesterol level

Question 16

Which of the following statements about confounding variables is correct?

Accepted Answer

Confounding variables are explanatory variables whose effects cannot be distinguished from another explanatory variable.

Question 17

A researcher wants to determine if a new teaching method improves student performance. She randomly assigns students to either the new method or the traditional method and compares their test scores. What is the control group?

Accepted Answer

Students using the traditional teaching method

Question 18

Which formula represents the probability of selecting a specific sample of size $$n$$ from a population of size $$N in a $$simple random sample?

Accepted Answer

$$P = \frac{1}{\binom{N}{n}}$$

Question 19

A survey is mailed to 1,000 randomly selected households, but only 30 respond. Which type of bias is most likely present?

Accepted Answer

Nonresponse bias

Question 20

Which of the following best explains why designed experiments can establish cause-and-effect relationships?

Accepted Answer

Because researchers manipulate explanatory variables and control other variables

Introduction to the Practice of Statistics: Data Collection and Experimental Design

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