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Unformatted text preview: e interval estimate is based on a
probability distribution known as the t distribution. • X −µ
In this case, follows t distribution. s/ n • This also holds for n > 30 as shown in previous slide. Slide 10 σ
s Unknown : Interval Estimate of a μ
Unknown : Interval Estimate of a Assume Normal Population Interval Estimate of µ x ± tα / 2 s
n where 1 α = the confidence coefficient tα/2 = the t value providing an area of α/2 in the upper tail of a t distribution with n 1 degrees of freedom s = the sample standard deviation Slide 11 t Distribution
The t distribution is a family of similar probability distributions.
s A specific t distribution depends on a parameter known as the degrees of freedom.
s A t distribution with more degrees of freedom has less dispersion.
s As the number of degrees of freedom increases, the difference between the t distribution and the standard normal probability distribution becomes smaller and smaller.
s The standard normal z values can be found in the
∞ infinite degrees ( ) row of th...
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- Spring '08