- Range: Highest value - Lowest value
- Quartiles: Values that divide ordered data into four equal parts
- Q1 (Lower Quartile): 25% of data is below this value
- Q2 (Median): 50% of data is below this value
- Q3 (Upper Quartile): 75% of data is below this value
- IQR (Interquartile Range): Q3 - Q1 (middle 50% spread)
This key facts covers Key Facts About Measures of Spread within Range & IQR for GCSE Mathematics. Revise Range & IQR in Statistics for GCSE Mathematics with 12 exam-style questions and 20 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 2 of 8 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Range & IQR
The range of a set of data is calculated by:
Explain why the interquartile range (IQR) is sometimes preferred over the range as a measure of spread.
Quick recall flashcards
What are quartiles?
Quartiles are values that divide an ordered dataset into four equal parts:
- Q1 (Lower quartile): 25% below
- Q2 (Median): 50% below
- Q3 (Upper quartile): 75% below
What is the range?
The range is the difference between the highest value and the lowest value in a dataset.
Range = Highest value - Lowest value