StatisticsCh8.2

# StatisticsCh8.2 - Stats Estimating the Mean You are...

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Stats: Estimating the Mean You are estimating the population mean, mu, not the sample mean, x bar. Population Standard Deviation Known If the population standard deviation, sigma is known, then the mean has a normal (Z) distribution. The maximum error of the estimate is given by the formula for E shown. The Z here is the z- score obtained from the normal table, or the bottom of the t-table as explained in the introduction to estimation . The z-score is a factor of the level of confidence, so you may get in the habit of writing it next to the level of confidence. Once you have computed E, I suggest you save it to the memory on your calculator. On the TI-82, a good choice would be the letter E. The reason for this is that the limits for the confidence interval are now found by subtracting and adding the maximum error of the estimate from/to the sample mean. Student's t Distribution When the population standard deviation is unknown, the mean has a Student's t distribution. The Student's t distribution was created by William T. Gosset, an Irish brewery worker. The brewery

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StatisticsCh8.2 - Stats Estimating the Mean You are...

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