Question 1

Which of the following best describes the difference between the mean and the median in terms of robustness to outliers?

Accepted Answer

The median is robust to outliers, while the mean is sensitive to them.

Question 2

Given the following data set: $$x = \{1, 2, 4, 4, 5\}$$, what is the value of the median?

Accepted Answer

$$4$$

Question 3

A researcher is analyzing the BMI of a population and finds the following summary: Mean = 25.8, Median = 25.4, SD = 4.5. Which of the following statements is most accurate?

Accepted Answer

The mean and median are close, suggesting a symmetric distribution.

Question 4

Which R function would you use to create a barplot of a categorical variable's frequency table?

Accepted Answer

barplot()

Question 5

Suppose you have the following data: $$x = \{1, 2, 2, 4, 5\}. $$What is the mode of this data set?

Accepted Answer

$$2$$

Question 6

Which of the following is NOT a robust measure of variability?

Accepted Answer

Standard Deviation

Question 7

Given the following summary statistics for 'Time until Death': Min = 0.6, Q1 = 2.3, Median = 3.5, Q3 = 4.25, Max = 10.0, what is the interquartile range (IQR)?

Accepted Answer

$$IQR = 4.25 - 2.3 = 1.95$$

Question 8

A boxplot is created for a data set. Which of the following statements about outliers is correct according to the 1.5*IQR rule?

Accepted Answer

Any value greater than Q3 + 1.5*IQR or less than Q1 - 1.5*IQR is considered an outlier.

Question 9

In the context of the asthma data, approximately what percentage of females have asthma?

Accepted Answer

$$12.3\%$$

Question 10

Which R function would you use to calculate the mean of a numeric vector x?

Accepted Answer

mean(x)

Question 11

A histogram is most appropriate for visualizing which type of data?

Accepted Answer

Numeric (continuous) data

Question 12

If a data set has extreme values (outliers), which measure of central tendency is LEAST affected?

Accepted Answer

Median

Question 13

Which of the following R code snippets would correctly filter a data frame 'df' to only include rows where the variable 'age' is greater than 18?

Accepted Answer

df[df$age \u003e 18, ]

Question 14

Suppose you have a data set with the following five-number summary: Min = 2, Q1 = 4, Median = 6, Q3 = 8, Max = 10. What is the range of the data?

Accepted Answer

$$10 - 2 = 8$$

Question 15

Which of the following best describes the purpose of the 'summary()' function in R?

Accepted Answer

It provides descriptive statistics such as Min, 1st Qu., Median, Mean, 3rd Qu., and Max.

Question 16

If you want to visualize the distribution of BMI categories (Normal, Overweight, Obese, Underweight) in a population, which plot would be most appropriate?

Accepted Answer

Barplot

Question 17

Which of the following is the correct formula for the sample standard deviation $$s of a $$data set $$x_1$$, $$x_2$$, ..., x_n$$?

Accepted Answer

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

Question 18

A data set has the following values: $$x = \{1, 2, 3, 4, 100\}. $$Which measure of central tendency would best represent the 'typical' value in this data set?

Accepted Answer

Median

Question 19

Which of the following statements about the range is correct?

Accepted Answer

The range is calculated as the difference between the maximum and minimum values.

Question 20

In R, which package is commonly used for data manipulation and visualization, as seen in the study materials?

Accepted Answer

tidyverse

Descriptive Statistics and Data Visualization Using R

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