Question 1

Which type of variable is 'Salary' as described in the academic salaries dataset?

Accepted Answer

Numeric, continuous

Question 2

Given the following data set: \{1, 3, -5, 4, -2\}, what is the median?

Accepted Answer

$$1$$

Question 3

Which of the following best describes the distribution shown in the histogram of 'Cost of Living Index' (Image 4)?

Accepted Answer

Skewed to the right

Question 4

What is the formula for the sample variance $$s^2 of a $$numeric variable?

Accepted Answer

$$s^2$$ = \frac{\sum_{i=1}^n (x_i - \bar{x}$$)^2$$}{n-1}$$

Question 5

Which measure of center and spread is most robust to outliers?

Accepted Answer

Median and interquartile range (IQR)

Question 6

A professor's salary is $$4,000 (in $$thousands of dollars), the mean salary is $$2,800$$, and the standard deviation is $$400. $$What is the z-score for this professor's salary?

Accepted Answer

$$z = 3$$

Question 7

Which plot is most appropriate for visualizing the distribution of a categorical variable such as 'Subject' in the academic salaries dataset?

Accepted Answer

Bar chart

Question 8

Given the correlation matrix for SAT.Score, HS.GPA, and College.GPA, which pair has the strongest linear association?

Accepted Answer

HS.GPA and College.GPA

Question 9

If a histogram of exam scores is symmetric and unimodal, which measure of center is most appropriate to summarize the data?

Accepted Answer

Mean

Question 10

Which of the following statements about correlation is TRUE?

Accepted Answer

Correlation is affected by outliers.

Question 11

A boxplot of savings (Image 10) shows a point above the upper whisker. What does this point represent?

Accepted Answer

An outlier

Question 12

Which of the following is a valid conclusion from a correlation of $$r = 0.88$$ between the number of radios and televisions in cities?

Accepted Answer

Cities with a higher number of radios tend to have a higher number of televisions.

Question 13

Which of the following best describes the distribution of ages of female cardiac patients (Image 5)?

Accepted Answer

Unimodal and approximately symmetric

Question 14

If you add an extreme outlier to a data set, which measure is most likely to change significantly?

Accepted Answer

Mean

Question 15

Given the formula for the z-score $$z = \frac{x_l - \bar{x}}{s}$$, what does a z-score of $$-2$$ indicate?

Accepted Answer

The value is two standard deviations below the mean.

Question 16

Which of the following is NOT a valid way to summarize a categorical variable?

Accepted Answer

Histogram

Question 17

A histogram of exam scores is shown to be skewed to the left. Which measure of center is likely to be greater?

Accepted Answer

Median

Question 18

Which of the following best describes the relationship between association and causation?

Accepted Answer

Causation always implies association.

Question 19

If the correlation between two variables is $$r = -0.98$$, what does this indicate?

Accepted Answer

A strong negative linear association

Question 20

Which of the following is true about the interquartile range (IQR)?

Accepted Answer

It is the difference between the first and third quartiles.

Descriptive Statistics: Summarizing and Visualizing Data

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