Vocabulary

Univariate data: Data with one variable, such as test scores.

Bivariate Data: Data with two variables, or pairs of numerical observations.

Mean: means average.

Median: It is the middle number of the data set when in order from the least to the greatest.

Mode: It is the number that occurred the most often.

Range: It is the difference between the highest and lowest values in the set.

Box and Whisker Plot: It shows measures of variation for a set of data. Also known as box plot.

The Five-Number Summary: It includes the minimum, Q1, median, Q3, and maximum values.

Q1: It is the first quartile or the median of the first half of the data set.  

Q3: It is the third quartile or the median of the second half of the data set.    

Interquartile range (IQR): It represents the middle 50%. It spans from the 25th percentile to the 75th percentile and is represented by the box in a boxplot. 

Concept

Identify measures of central tendency. 

Rules

Identify the basic vocabuary used for descriptive statistics.

Example

Which of the following measures represents the middle 50% of a data set? 

Hint: This measure also represents the length of the box on a boxplot.

Solution

The interquartile range (IQR) represents the middle 50%. It spans from the 25th percentile to the 75th percentile and is represented by the box in a boxplot. 

Pre-requisite Skills

Select an Appropriate Display (7.11.5)

Find Mean, Median, Mode and, Range Using Graphs (6.2.9)

Find the Mean (5.8.5)

Find the Mode (5.8.6)

Find Median (5.8.7)

Find the Range (5.8.8)