Khan Academy
Range and Interquartile Range
Compare the full spread vs. the middle 50%.
Watch on YouTubeTwo ways to measure how spread out a data set is.
Read this first — it covers the idea in plain language with a worked example.
Range is the simplest measure of spread: the largest value minus the smallest value. It's quick, but a single extreme value can stretch it a lot.
Find the range of 2, 5, 7, 8, 11, 14, 20.
IQR measures the spread of the middle 50% of the data. Because it ignores the extreme high and low values, it is less affected by outliers than the range.
Tip
IQR = upper quartile (Q3) − lower quartile (Q1).
Watch the main video, then check the second take if you want another explanation.
Compare the full spread vs. the middle 50%.
Watch on YouTubeMeasure the spread of the middle half of your data.
Watch on YouTubeTry a worksheet or work through some problems before the quiz.
A couple of questions to make sure this topic stuck. Retake as many times as you want.
Spread: Range & IQR
Find the range of 2, 5, 7, 8, 11, 14, 20.