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Requirements
simple random sample
the population standard deviation is known
either or both of these conditions are satisfied: The population is normally distributed or n>30
Point Estimate of the Population Mean
the sample mean (x w/line) is the best point estimate of the population mean (µ)
Sample Mean
for all populations, the sample mean is an
unbiased estimator
of the population mean
for many populations, the distribution of sample means tends to be more consistent (with
less
variation
) than the distributions of other sample statistics
the
margin of error
E is the maximum likely difference observed between the sample mean and the
population mean
Procedure for constructing a confidence interval
verify that the requirements are satisfied
find the critical value (z sub alpha over 2) that corresponds to the desired degree of confidence
evaluate the margin of error
find the values of (x bar minus E) and (x bar plus E). Substitute those values in the general
format of the confidence interval
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This note was uploaded on 04/17/2008 for the course MATH unknown taught by Professor Sapko during the Fall '08 term at Mass Colleges.
 Fall '08
 Sapko
 Statistics, Standard Deviation

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