- Always arrange data in order before finding quartiles
- Be careful with even/odd numbers when finding medians of halves
- Don't include the median when splitting data into halves for large datasets
- Show your working - especially when finding Q1 and Q3
- Check your answer makes sense - IQR should be less than range
- Units matter - range and IQR have the same units as the original data
- Use IQR for comparisons when asked about consistency or spread
This exam tips covers Exam Tips for Range and IQR 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 6 of 8 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
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