agronomist wanted to compare the effect of three levels of moisture on the dry m
ID: 3155763 • Letter: A
Question
agronomist wanted to compare the effect of three levels of moisture on the dry matter yield of barley used as a forage crop. For her/his experimental design she/he chose a completely randomized design. At maturity she/he clipped each plot and measured the dry matter of forage produced. She/he obtained the yields (kilograms per plot) shown below.
Assume that the data are normally distributed and have equal variances. Perform all the appropriate tests for a, b and c.
Answer the following research question: Are yields the same among treatments? If there are differences determine where differences occur. Perform the appropriate tests
Now assume that the data are not normally distributed but have equal variances. Repeat above using the appropriate tests
c. Now assume that each field plot is a block and a Randomized Block Design was used. Repeat above using the appropriate tests.
(Block)
Moisture
Field Plot
Low
Moderate
High
1
35.6
41.9
38.8
2
31.5
37.1
30.8
3
27.4
33.8
31.1
4
33
36.6
31.4
5
31
33.8
31.9
6
24.8
26.7
26.7
(Block)
Moisture
Field Plot
Low
Moderate
High
1
35.6
41.9
38.8
2
31.5
37.1
30.8
3
27.4
33.8
31.1
4
33
36.6
31.4
5
31
33.8
31.9
6
24.8
26.7
26.7
Explanation / Answer
a)
here p value is > 0.05, so we accept H0.
b) we use one way aNova here. using excel for the analysis, we get One factor ANOVA Mean n Std. Dev 30.55 6 3.888 Group 1 34.98 6 5.027 Group 2 31.78 6 3.916 Group 3 32.44 18 4.482 Total ANOVA table Source SS df MS F p-value Treatment 62.831 2 31.4156 1.69 .2176 Error 278.612 15 18.5741 Total 341.443 17 Since p value is > 0.05, we accept H0.
c)
Kruskal-Wallis Test Median n Avg. Rank 31.25 6 7.50 Group 1 35.20 6 12.75 Group 2 31.25 6 8.25 Group 3 31.70 18 Total 3.402 H (corrected for ties) 2 d.f. .1825 p-value multiple comparison values for avg. ranks 7.38 (.05) 9.05 (.01)Related Questions
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