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SECTION 5.2 SUMMARY

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μˉx=μσˉx=σn

The sample mean ˉx is an unbiased estimator of the population mean μ and is less variable than a single observation. The standard deviation decreases in proportion to the square root of the sample size n. This means that to reduce the standard deviation by a factor of C, we need to increase the sample size by a factor of C2.