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Counterexample bank

Part C is won by knowing which tempting claims are false. 148 counterexamples; 85 free. The rest come with the Notes pack.

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#1 · Probability & Statistics › Sampling and Design of Experiments

“Systematic sampling is always at least as efficient as SRS” — false

Counterexample: A population with a periodic pattern of period k, sampled every k-th unit

Every sampled unit falls at the same phase, so the sample can be maximally unrepresentative.

statisticssampling