7.4 Determining the Sample Size

You can find the appropriate sample size to estimate the difference between a pair of parameters with a specified sampling error (SE) and degree of reliability by using the method described in Section 5.5. That is, to estimate the difference between a pair of parameters correct to within SE units with confidence level (1α), let zα/2 standard deviations of the sampling distribution of the estimator equal SE. Then solve for the sample size. To do this, you have to solve the problem for a specific ratio between n1 and  n2. Most often, you will want to have equal sample sizes—that is, n1=n2=n. We will illustrate the procedure with two examples.

Example 7.6 Finding the Sample Sizes for Estimating (μ1μ2) —Comparing ...

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