Histograms
Histograms display continuous grouped data using bars whose area (not height) represents frequency. This topic requires students to calculate frequency density and interpret histograms with unequal class widths.
What You'll Learn
- Calculating frequency density (frequency divided by class width)
- Drawing histograms with unequal class widths
- Reading frequencies from a histogram using area
- Estimating the median and quartiles from a histogram (not on the current Cambridge 0580 syllabus)
Watch Out For These Mistakes
Students make these errors again and again. Knowing them in advance gives you a head start.
Plotting frequency instead of frequency density on the y-axis
Confusing histograms with bar charts (histograms have no gaps between bars)
Calculating class width incorrectly for grouped data
What Examiners Say About Histograms
Insights pulled from Cambridge IGCSE (0580) examiner reports — the exact mistakes candidates make every year.
- Common Mistake●●●●●
In probability without replacement, the denominator DECREASES by 1 for each subsequent pick (13 → 12 → 11...). Getting 104/169 instead of the correct answer usually means you forgot this.
Source: CIE 0580 · Feb/March 2024 · Paper 2 · Q25
- Common Mistake●●●●●
For 'exactly one green button' out of two picks, there are TWO orderings: green-then-not OR not-then-green. Calculate one product and DOUBLE it (or add both products).
Source: CIE 0580 · May/June 2023 · Paper 4 · Q15
- Technique●●●●●
In a histogram, bar HEIGHT = frequency density (frequency ÷ class width). Find the scale using a bar whose frequency AND width you know, then apply it to the others.
Source: CIE 0580 · Feb/March 2022 · Paper 4 · Q5b
Based on 3of 500+ insights extracted from CIE 0580 examiner reports (2018–2024).
Exam Coverage
This topic appears in the Cambridge IGCSE past papers. Our AI tutor can help with it on any question.
Useful for this topic:
Related Topics
Frequency Tables
Frequency tables organise raw data into categories or class intervals for analysis. Students must construct tables, calculate totals, and use them to find averages and draw statistical diagrams.
Cumulative Frequency
Cumulative frequency diagrams show running totals and are used to estimate the median, quartiles and interquartile range. Students draw the characteristic S-shaped curve and read off values at key percentile positions.
Mean, Median and Mode
Averages are fundamental to data analysis. Students must calculate mean, median, mode and range from raw data, frequency tables and grouped data, and understand which average is most appropriate in different contexts.
Ready to Master Histograms?
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Worked examples and data interpretation guides