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Unformatted text preview: are paired by Test Condition
(“position on the original cylinder”?) The scatterplot seem s to
indicate that the pairing variable will not prove very useful.
b. A 95% confidence interval is given by Normal
High
D=NH n
15
15
15 mean
47.9
90.1
42.2 s
3.93
1.96
4.34 B ox Plot of multiple variables
Normal and High Strength Concrete Peak Stress
100 90 80 70 . A normal probability plot 60 50 of the differences indicates the validity of using the t distributi on.
The huge distance of this 95% confidence interval from zero
indicates that there is a big difference between the mean peak stress for the normal versus high stress mixes.
40 Normal High 43. The statistics are in the table. The standard error is 5.98.
n
mean
s
a. The normal probability plot does not exhibit noteworthy curvature, so there is no
D=OD
15
38.6
23.2
reason to doubt that the data are not normal.
b. The lower confidence bound uses t.05;14 = 1.761, and is given by 38.6  1.761(5.98) = 38.6  10.5 = 49.1. We are 95%
confidence that the mean number of months between the onset of Cushing’s disease and its diagnosis is no greater than
49.1 months.
c. In...
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This note was uploaded on 09/17/2012 for the course STAT 312 taught by Professor Chung during the Spring '04 term at University of Wisconsin.
 Spring '04
 Chung
 Standard Error

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