Sec 14.2 Sign test for a single population inferences
Example
Consider the following sample of 10 observations
8.4
16.9
15.8
12.5
10.3
4.9
12.9
9.8
23.7
7.3
9
(a) At the 5% significance level, does the data provide the sufficient evidence to conclude
that the median exceeds 9? Use the binomial distribution.
(b) Repeat part (a) by using the normal approximation to binomial distribution.
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Wilcoxon Rank Sum Test
A university statistics professor was concerned about the detrimental effects of poor
mathematics background on her students. She randomly selected 15 students and divided
them according to math background. Their semester average were the following
Fewer than 2 years
Two or more
of high school algebra
of high school algebra
58
84
61
92
81
75
64
67
74
83
43
81
65
52
74
(a) At the 5% significance level, do the data provide sufficient evidence to conclude that
students with fewer than 2 years of high school algebra have a lower mean semester
average than those with 2 or more years?
(b) Repeat (a) using normal approximation.
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 Winter '07
 Dan
 Statistics, Statistical tests, Nonparametric statistics, Wilcoxon signedrank test, U.S. Federal Highway Administration

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