Making Sense of Large Datasets
📊 Making Sense of Large Datasets
Imagine you're analyzing the heights of all students in your school. With hundreds of measurements like 165.2cm, 170.8cm, 163.4cm, it would be impossible to work with each individual value. This is where grouped data comes to the rescue - we organize data into intervals or classes to make it manageable and meaningful.
Mathematics glossary
- What is class width?
- Class width is the size of each class interval. For '10 ≤ x < 20', the class width is 20 - 10 = 10. Equal class widths make data easier to analyze.
- What is grouped data?
- Grouped data is when individual data values are organized into classes or intervals. For example, heights might be grouped as 150-160cm, 160-170cm, etc.
Earn the mark scheme marks
💡 Exam Tips for Grouped Data
- Reading intervals: "150 ≤ h < 160" means 150 is included, 160 is not
- Midpoints: Always (lower boundary + upper boundary) ÷ 2
- Class width: Should be consistent across all intervals
- Modal class vs mode: We can only find the modal class, not the exact mode
- Estimated values: Remember to state that mean and median are estimates
- Units: Always include units in your final answers
- Show working: Always show your calculation steps for full marks
Now try it yourself
Quiz · Question 1 of 14
A frequency table uses the class intervals shown below. | Speed, s (mph) | Frequency | |---|---| | 0 < s ≤ 20 | 4 | | 20 < s ≤ 40 | 11 | | 40 < s ≤ 60 | 9 | | 60 < s ≤ 80 | 2 | A car travels at exactly 40 mph. Which class interval does this value belong to?
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This topic in real past papers
Every real exam question we've found on grouped data, with a full worked answer.
AQA Paper 2
Two of the four sittings we have full papers for require estimating the mean from a grouped frequency table as part of a larger question.
Edexcel Paper 1
Two of the three sittings we have full papers for start from a grouped frequency table and ask for a statistic or a graph built from it.