The moment your “perfect” answer loses marks
It’s a familiar IB Math moment: you do the calculation cleanly, your numbers look sensible, and then the markscheme asks for “a comment on the sampling limitations.” Suddenly, your confident conclusion feels like it’s standing on a floor made of paper.
That discomfort is the point. In IB Math, statistics is not only about processing data; it’s about judging how much trust the data deserves. A sample can be computed correctly and still be a shaky foundation for a real-world claim. Sampling limitations are how IB checks whether you can tell the difference.

Quick checklist: what IB wants you to notice
When an IB Math question hints at sampling, scan for these high-yield limitations:
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Who is missing? (undercoverage)
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Who chose to join? (voluntary response)
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How were people found? (convenience sampling)
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How many were sampled? (small sample size, unstable results)
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What made answering hard? (non-response bias)
To practise these quickly, build short drills from the Statistics and Probability Questionbank and ask RevisionDojo’s AI Chat to mark your evaluation sentences, not just your calculations.
Why IB Math keeps coming back to sampling limitations
Because IB is policing overgeneralisation
Most weak conclusions in IB Math have the same hidden flaw: they quietly jump from “this sample” to “everyone.” Examiners reward students who restrict claims to the group actually studied, or who explicitly state that the results .

