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WEEK 6 HOMEWORK
1222.
A physician who specializes in weight control has three different diets she recommends. As an
experiment, she randomly selected 15 patients and then assigned 5 to each diet. After three weeks the
following weight losses, in pounds, were noted. At the .05 significance level, can she conclude that there
is a difference in the mean amount of weight loss among the three diets?
Plan A
Plan B
Plan C
5
6
7
7
7
8
4
7
9
5
5
8
4
6
9
Anova: Single Factor
SUMMARY
Groups
Count
Sum
Average
Variance
Column 1
5
25
5
1.5
Column 2
5
31
6.2
0.7
Column 3
5
41
8.2
0.7
ANOVA
Source of Variation
SS
df
MS
F
Pvalue
F crit
Between Groups
26.1333
2
13.0667
13.5172
0.000844
3.88529
Within Groups
11.6
12
0.96667
Total
37.7333
14
Null Hypothesis (Ho): μA = μB = μC
Alternative Hypothesis (Ha): At least on of them is equal
Test statistics
F = 13.5172
Pvalue is 0.0008
Since pvalue is less than 0.05 level of significance, we have sufficient evidence to reject null hypothesis.
We can conclude that there is a difference in the mean amount of
weight loss among the three diets
1228.
Three assembly lines are used to produce a certain component for an airliner. To examine the
production rate, a random sample of six hourly periods is chosen for each assembly line and the number
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of components produced during these periods for each line is recorded. The output from a statistical
software package is:
Groups
Count
Summary
Sum
Average
Variance
Line A
6
250
41.66667
0.266667
Line B
6
260
43.33333
0.666667
Line C
6
249
41.5
0.7
ANOVA
Source of Variation
SS
df
MS
F
Pvalue
Between Groups
12.33333
2
6.166667
11.32653
0.000101
Within Groups
8.166667
12
0.544444
Total
20.5
17
a.
Use a .01 level of significance to test if there is a difference in the mean production of the three assembly
lines.
Since pvalue in the table is 0.000101, which is less than significant level 0.01, we can reject
null hypothesis. Conclusion: there is a difference in the mean production of the three assembly
lines.
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 Fall '10
 RandallBarcus
 Regression Analysis, Null hypothesis, independent variables

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