Wild irises are beautiful flowers found throughout the United States, Canada, and northern Europe. This problem concerns the length of the sepal (leaf-like part covering the flower) of different species of wild iris. Data are based on information taken from an article by R. A. Fisher in Annals of Eugenics (Vol. 7, part 2, pp. 179 -188). Measurements of sepal length in centimeters from random samples of Iris setosa (I), Iris versicolor (II), and Iris virginica (III) are as follows below.
I | II | III |
5.1 | 5.5 | 6.6 |
4.7 | 6.8 | 5.4 |
5.3 | 6.2 | 4.4 |
5.9 | 4.9 | 7.2 |
4.1 | 5.3 | 5.1 |
5.4 | 6.9 | 6.5 |
5.7 | 5.6 | |
6.4 |
(b) Find SSTOT, SSBET, and
SSW and check that SSTOT =
SSBET + SSW. (Use 3 decimal places.)
SSTOT | = | |
SSBET | = | |
SSW | = |
Find d.f.BET, d.f.W,
MSBET, and MSW. (Use 4 decimal
places for MSBET, and
MSW.)
dfBET | = | |
dfW | = | |
MSBET | = | |
MSW | = |
Find the value of the sample F statistic. (Use 2 decimal
places.)
What are the degrees of freedom?
(numerator)=
(denominator)=
(f) Make a summary table for your ANOVA test.
Source of Variation |
Sum of Squares |
Degrees of Freedom |
MS | F Ratio |
P Value | Test Decision |
Between groups | ---Select--- p-value > 0.100 0.050 < p-value < 0.100 0.025 < p-value < 0.050 0.010 < p-value < 0.025 0.001 < p-value < 0.010 p-value < 0.001 | ---Select--- Do not reject H0. Reject H0. | ||||
Within groups | ||||||
Total |
Applying ANOVA"
Source of Variation | SS | df | MS | F | P-value |
Between Groups | 1.5098 | 2 | 0.7549 | 1.0651 | 0.3654 |
Within Groups | 12.7569 | 18 | 0.7087 | ||
Total | 14.2667 | 20 |
b)
SSTOT | 14.2667 |
SSBET | 1.5098 |
SSW | 12.7569 |
dfBET | 2 |
dfW | 18 |
MSBET | 0.7549 |
MSW | 0.7087 |
value of the sample F statistic =1.065
(numerator)=2
(denominator)=18
Source of Variation | SS | df | MS | F | P-value | Decision |
Between Groups | 1.5098 | 2 | 0.7549 | 1.0651 | p value >0.10 | fail to reject Ho |
Within Groups | 12.7569 | 18 | 0.7087 | |||
Total | 14.2667 | 20 |
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