Quartiles and Interquartile Range

Front

What is a quartile?

Back

A quartile is a type of quantile that divides a data set into four equal parts, each containing 25% of the data.

Front

What is the Interquartile Range (IQR)?

Back

The Interquartile Range (IQR) is the difference between the upper quartile (Q3) and the lower quartile (Q1). It measures the spread of the middle 50% of the data.

Front

How do you find the lower quartile (Q1)?

Back

To find Q1, arrange the data in ascending order and find the median of the lower half of the data set.

Front

How do you find the upper quartile (Q3)?

Back

To find Q3, arrange the data in ascending order and find the median of the upper half of the data set.

Front

What is the median of a data set?

Back

The median is the middle value of a data set when it is arranged in ascending order. If there is an even number of values, the median is the average of the two middle values.

Front

True or False: The median is always equal to one of the values in the data set.

Back

False. The median may not be one of the actual data values, especially if the number of values is even.

Front

What do quartiles split data up into?

Back

Quartiles split data into four equal parts.

Front

If the lower quartile (Q1) is 13.5, what does this indicate about the data?

Back

This indicates that 25% of the data values are less than or equal to 13.5.

Front

What does the upper quartile (Q3) represent?

Back

Q3 represents the value below which 75% of the data fall.

Front

How do you calculate the IQR if Q1 is 13.5 and Q3 is 46.5?

Back

IQR = Q3 - Q1 = 46.5 - 13.5 = 33.