Question
How does stratified random sampling improve a sample versus simple random sampling?
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Answer
It ensures subgroup representation by sampling within each stratum.
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Question
How is the standard error of the sample mean computed when population standard deviation is known?
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Answer
SE(arx)=σ/n
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Question
Why is a prediction interval wider than a confidence interval for the mean response?
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Answer
It includes individual-observation variability in addition to mean uncertainty.
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Question
What z-critical value is used for a 95% confidence interval?
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Answer
1.96
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