Foundations: Descriptive Stats and Basics

What is the median of the dataset 3, 3, 4, 6, 9?

4

What is the mode of the dataset 2, 4, 4, 5, 6?

4

Which measure is most affected by an extreme outlier?

Mean

What is the range of the dataset 10, 12, 15, 20?

10

If you add the same constant k to every data point, what happens to the standard deviation?

It is unchanged.

In a perfectly symmetric distribution, what is true about the mean and median?

Mean = Median

What is the 75th percentile also known as?

Third quartile

What is the formula for the interquartile range (IQR)?

Q3 − Q1

What does a histogram with a long right tail indicate?

Right-skewed

In what units is variance measured?

Square of units

What does a standard boxplot not display?

Mean

What does a z-score represent?

Distance from mean in standard deviation units

If the mean is 50 and the standard deviation is 10, what is the z-score for a value of 70?

2

Which of the following is an example of a discrete variable?

Number of calls

What does standardizing data using z-scores change?

Center and spread, but not shape.