Interquartile Range (IQR)

Front

What is the interquartile range (IQR)?

Back

The interquartile range (IQR) is a measure of statistical dispersion, representing the range between the first quartile (Q1) and the third quartile (Q3) in a data set.

Front

How do you calculate the interquartile range?

Back

IQR = Q3 - Q1, where Q3 is the third quartile and Q1 is the first quartile.

Front

What does the first quartile (Q1) represent?

Back

Q1 is the median of the lower half of a data set, meaning 25% of the data points are below this value.

Front

What does the third quartile (Q3) represent?

Back

Q3 is the median of the upper half of a data set, meaning 75% of the data points are below this value.

Front

If Q1 is 3.5 and Q3 is 10.5, what is the IQR?

Back

IQR = 10.5 - 3.5 = 7.

Front

What is the purpose of calculating the IQR?

Back

The IQR is used to measure the spread of the middle 50% of data points and to identify outliers.

Front

How can you find the IQR using a five-number summary?

Back

The five-number summary includes the minimum, Q1, median, Q3, and maximum. The IQR is calculated as Q3 - Q1.

Front

What is an outlier in a data set?

Back

An outlier is a data point that is significantly different from other observations, often identified using the IQR.

Front

How do you identify outliers using the IQR?

Back

Outliers can be identified as any data point that is below Q1 - 1.5*IQR or above Q3 + 1.5*IQR.

Front

What is the difference in IQR between two data sets?

Back

The difference in IQR between two data sets shows how the spread of the middle 50% of values compares between the two sets.