Descriptive statistics in R Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of descriptive statistics?

Descriptive statistics summarize and describe the main features of a dataset using numbers and graphs, making data easier to understand.

beginner

Name three common measures of central tendency.

The three common measures are mean (average), median (middle value), and mode (most frequent value).

beginner

What does the standard deviation tell us about data?

Standard deviation shows how spread out the data is around the mean. A small value means data points are close to the mean; a large value means they are spread out.

beginner

In R, which function gives a quick summary of a dataset including min, max, median, and quartiles?

The function summary() provides a quick overview of these statistics for each column in a dataset.

intermediate

What is the difference between variance and standard deviation?

Variance measures the average squared distance from the mean, while standard deviation is the square root of variance, giving spread in the original units.

Which measure of central tendency is least affected by extreme values?

A Mean

B Range

C Mode

D Median

The median is the middle value and is not influenced by very high or low values, unlike the mean.

What does the function sd() in R calculate?

A Median

B Standard deviation

C Mean

D Variance

sd() calculates the standard deviation, which measures data spread around the mean.

Which of the following is NOT a measure of spread?

A Mean

B Variance

C Range

D Standard deviation

Mean is a measure of central tendency, not spread.

What does the summary() function in R return for numeric data?

A Only mean and median

B Only standard deviation

C Min, 1st quartile, median, mean, 3rd quartile, max

D Only mode

summary() returns a set of descriptive statistics including min, quartiles, median, mean, and max.

If data points are very close to the mean, what can we say about the standard deviation?

A It is small

B It is zero

C It is large

D It is negative

A small standard deviation means data points are close to the mean.

Explain the main types of descriptive statistics and their roles in understanding data.

Think about how we describe the center and spread of data.

Describe how you would use R functions to get a quick overview of a dataset's descriptive statistics.

Focus on common R functions for descriptive stats.