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Unformatted text preview: xU 2.5% Interval Estimation σ Known Example
Find an interval symmetrically distributed around the population
mean that includes 95% of the sample means.
Sampling distribution: µ= 6; σ = for n = 25
38 x 3
x 2.5% xL 95%
μ xU 2.5% Interval Estimation σ Known Example
Find an interval symmetrically distributed around the population
mean that includes 95% of the sample means.
Sampling distribution: µ= 6; σ = for n = 25
38 x 3
x find zscores for 2.5% and 97.5%: z = ±1.96 2.5% xL 95% xU 1.96 μ 1.96 2.5% Interval Estimation σ Known Example
Find an interval symmetrically distributed around the population
mean that includes 95% of the sample means.
Sampling distribution: µ= 6; σ = for n = 25
38 x 3
x find zscores for 2.5% and 97.5%: z = ±1.96 find corresponding sample means:
x−
µ
z= σx x 2.5% xL 95% xU 1.96 μ 1.96 2.5% Interval Estimation σ Known Example
Find an interval symmetrically distributed around the population
mean that includes 95% of the sample means.
Sampling distribution: µ= 6; σ = for n = 25
38 x 3
x find zscores for 2.5% and 97.5%: z = ±1.96 find corresponding sample means:
−
z = xσ µ x
x
low tail:
er
u
pper tail:
− .96 = x−µ
1
σx 1.96 = x−µ
σx Interval Estimation use z values corresponding to 95% 2.5% xL 95% xU 1.96 μ 1.96 2.5% σ Known Example
Find an interval symmetrically distributed around the population
mean that includes 95% of the sample means.
Sampling distribution: µ= 6; σ = for n = 25
38 x 3
x find zscores for 2.5% and 97.5%: z = ±1.96 2.5% find corresponding sample means:
−
z = xσ µ x
x
lower tail :
upper tail : Interval Estimation −1.96 = x −µ
3
−5.88 = x − µ 1.96 = x −µ
3
5.88 = x − µ multiply by standard error of 3 xL 95% xU 1.96 μ 1.96 2.5% σ Known Example
Find an interval symmetrically distributed around the population
mean that includes 95% of the sample means.
Sampling distribution: µ= 6; σ = for n = 25
38 x 3
x find zscores for 2.5% and 97.5%: z = ±1.96 find corresponding sample means:
−
z = xσ...
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This document was uploaded on 03/05/2014.
 Spring '13

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