When determining the sample size,if the population standard deviation,σ is unknown and an estimate is used,the standard deviation should be re-estimated once the sample has been drawn.Next a revised confidence interval should be calculated to determine the precision level actually obtained.

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Quizplus · Accepted Answer

This statement is true. When the population standard deviation is unknown and an estimate is used, the sample standard deviation is often used as an estimate. However, once the sample has been drawn and the sample standard deviation is calculated, it's important to use that value to re-estimate the population standard deviation. Then a revised confidence interval can be calculated to determine the actual level of precision obtained in the sample.

When Determining the Sample Size,if the Population Standard Deviation,σ Is