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NSWMaths Standard 2Quick questions
Year 11: Data Analysis
Quick questions on Data collection and sampling for HSC Maths Standard 2
5short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What are the three sampling methods?Show answer
NESA names three ways to choose a sample. Each aims to be fair, but they differ in how they do it.
What is designing a stratified sample?Show answer
Stratified sampling is the method NESA examines most, because it involves a calculation. The idea is simple: each stratum should contribute to the sample in the same proportion as it appears in the population. The tool is the sampling fraction:
What is sample size?Show answer
A bigger sample generally gives a more reliable estimate, because random sampling error shrinks as the sample grows. But a bigger sample also costs more time and money, so you balance accuracy against cost. There is no single "correct" size in Standard 2; what matters is that the sample is large enough to be reliable and is chosen by a fair method. A small sample, or a large sample chosen by a biased method, is worse than a modest sample chosen well.
What are bias?Show answer
Bias is any systematic tendency for a sample to differ from the population, so that it consistently over- or under-states the truth. Bias is not bad luck; it is a flaw built into how the data was collected, and a larger sample does not fix it. The common sources are:
What is not checking the strata add to the sample size?Show answer
Always confirm the parts total the required sample; if they do not, the fraction or the arithmetic is wrong.
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