Sampling
Sampling methods determine how data is collected for a statistical investigation. Students must understand random, systematic and stratified sampling, and evaluate the strengths and limitations of each method.
Not on the current Cambridge 0580 syllabus (2025-2027).
What You'll Learn
- Understanding the need for sampling rather than a census
- Carrying out random, systematic and stratified sampling
- Calculating the number of items in each stratum for stratified sampling
- Evaluating bias and representativeness in sampling methods
Watch Out For These Mistakes
Students make these errors again and again. Knowing them in advance gives you a head start.
Confusing stratified sampling with quota sampling
Rounding stratum sizes incorrectly so the total does not match the sample size
Not recognising sources of bias in convenience or voluntary sampling
What Examiners Say About Sampling
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.
Scatter Graphs
Scatter graphs show the relationship between two variables and are used to identify correlation. Students plot data, draw lines of best fit, and use them to make predictions, while understanding the limitations of extrapolation.
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.
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Worked examples and data interpretation guides