Question 1

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

Accepted Answer

A parameter is a numerically-valued attribute of a model representing the entire population, while a statistic is a value calculated from data to summarize aspects of the sample.

Question 2

A researcher wants to compare the heights of students in two different universities. Which graphical method is most appropriate for comparing the shape, center, and spread of the two distributions?

Accepted Answer

Boxplot

Question 3

Which of the following statements about the area principle is correct?

Accepted Answer

The area occupied by a part of a graph should be proportional to the magnitude of the value it represents.

Question 4

A survey is conducted by inviting people to respond online. Which type of bias is most likely to affect the results?

Accepted Answer

Voluntary response bias

Question 5

Suppose a dataset of exam scores is shifted by adding 10 points to every score. Which of the following statements is true?

Accepted Answer

The mean and median will increase by 10, but the standard deviation and IQR will remain unchanged.

Question 6

A researcher randomly selects 5 classrooms and surveys all students in those classrooms. What sampling method is being used?

Accepted Answer

Cluster sampling

Question 7

Which of the following is NOT a requirement for a valid confidence interval?

Accepted Answer

A sample size equal to the population size

Question 8

A distribution of test scores is unimodal and symmetric. According to the 68–95–99.7 Rule, what percentage of scores should fall within 2 standard deviations of the mean?

Accepted Answer

$$95\%$$

Question 9

Which of the following best describes a z-score?

Accepted Answer

A z-score tells how many standard deviations a value is from the mean, and in which direction.

Question 10

A hospital wants to estimate the average recovery time for a new treatment. They randomly assign patients to either the new treatment or the standard treatment and compare recovery times. What type of study is this?

Accepted Answer

Experiment

Question 11

Which of the following is a quantitative variable?

Accepted Answer

Number of books read in a month

Question 12

In a contingency table showing survival status (survived/died) and ticket class (first/second/third) for Titanic passengers, which percentage represents the conditional distribution of survival status for first-class passengers?

Accepted Answer

The percentage of first-class passengers who survived.

Question 13

Which of the following is a major advantage of using boxplots to compare groups?

Accepted Answer

Boxplots are ideal for comparing several groups side-by-side.

Question 14

A researcher wants to study the effect of a new fertilizer on plant growth. She randomly assigns plants to two groups: one receives the new fertilizer, the other does not. She measures the height after 8 weeks. Which is the response variable?

Accepted Answer

Plant height after 8 weeks

Question 15

Which of the following is an example of a lurking variable in an observational study?

Accepted Answer

A variable that influences the response variable but is not included in the study.

Question 16

A sample of 100 people is drawn from a population of 10,000. Which statement about sample size is correct?

Accepted Answer

The sample size is important, not the fraction of the population.

Question 17

Which of the following is a common mistake when interpreting percentages in contingency tables?

Accepted Answer

Confusing the percentage of passengers who were in first class and survived with the percentage of first-class passengers who survived.

Question 18

A researcher multiplies every value in a dataset by 3. What happens to the mean and standard deviation?

Accepted Answer

Both the mean and standard deviation are multiplied by 3.

Question 19

Which of the following best describes Simpson’s paradox?

Accepted Answer

A situation where the overall average is misleading due to unfair averaging over different groups.

Question 20

A hypothesis test yields a very small $$P-$$value. What does this imply?

Accepted Answer

The pattern observed in the data reflects something real and not just random variability.

Introductory Statistics: Data Collection, Description, and Analysis

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