Summary statistics in R Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are summary statistics?

Summary statistics are numbers that describe and summarize data, like the average, median, or spread. They help us understand the main features of data quickly.

beginner

What does the mean tell us about data?

The mean is the average value. It adds all numbers together and divides by how many numbers there are. It shows the central point of the data.

intermediate

What is the difference between mean and median?

Mean is the average of all values. Median is the middle value when data is sorted. Median is better when data has very high or low values that can skew the mean.

intermediate

What does the standard deviation measure?

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

beginner

How can you get summary statistics in R for a numeric vector?

Use the summary() function on the vector. It gives minimum, 1st quartile, median, mean, 3rd quartile, and maximum values.

Which summary statistic is the middle value when data is sorted?

A Standard deviation

B Mean

C Mode

D Median

The median is the middle value when data is arranged in order.

What does a high standard deviation indicate?

A Data points are spread out from the mean

B Data has no variation

C Mean and median are equal

D Data points are close to the mean

High standard deviation means data points are spread out from the average.

In R, which function gives a quick summary of a numeric vector?

A mean()

B summary()

C sd()

D median()

The summary() function provides min, quartiles, median, mean, and max.

If data has extreme values, which statistic is better to describe the center?

A Median

B Mean

C Standard deviation

D Range

Median is less affected by extreme values than mean.

What does the range of data show?

A Middle value

B Average value

C Difference between max and min values

D Spread around the mean

Range is the difference between the largest and smallest values.

Explain what summary statistics are and why they are useful.

Think about how you describe a group of numbers quickly.

Describe how you would get and interpret summary statistics for a numeric dataset in R.

Imagine you have a list of exam scores and want to know the main points.