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Statistics
Quick questions on Statistical sampling: populations, samples and sampling methods - Edexcel A-Level Maths
4short 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 random sampling methods?Show answer
Systematic sampling takes every th member from an ordered list after a random start, where . It is quick to administer from an ordered list, but a periodic pattern in the list at the same interval as can bias the sample. Stratified sampling divides the population into groups (strata) and samples each in proportion to its size, which represents subgroups well; the size taken from each stratum is the stratum's size multiplied by the overall sampling fraction.
What are non-random sampling methods?Show answer
Quota sampling fills set numbers from each group without random selection, and opportunity (convenience) sampling uses whoever is available. Both are quick and cheap but can be biased and do not support probability statements. The key distinction from stratified sampling is that quota sampling does not select randomly within each group, so a confident probability statement about the population cannot be justified.
What is q1?Show answer
A school of 800 students has 480 girls and 320 boys. Describe how to take a stratified sample of 50. [3 marks]
What is q2?Show answer
Give one advantage and one disadvantage of an opportunity sample. [2 marks]
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