Question 464762: 1.What is the difference between a parametric test and one that is nonparametric?
2.What is the difference between the ANOVA test from last week and the Kruskal-Wallis Test from Chapter 16?
3. Conduct a Kruskal-Wallis Test on the following problem. Be sure to show all steps and explain your conclusion.
The National Turkey Association wants to experiment with three different feed mixtures for very young turkeys. Since no experience exists regarding the three mixtures, no assumptions can be made about the distribution of weights. The Kruskal-Wallis test must be used to test whether the turkeys are equal in weight after eating the feed for a specified length of time. Five young turkeys were given feed A, six were given feed B, and five were given feed C. Test at the .05 level whether the mean weights of the turkeys who ate feed A, feed B, and feed C are equal.
Feed mixture A Feed mixture B Feed mixture C
10.9 10.7 10.6
11.2 10.8 11.3
11.3 11 11.9
12 11.3 12
12.1 12 12.4
12.6
Answer by studentabc(1)   (Show Source):
You can put this solution on YOUR website! 1. A parametric test is based directly on statistics derived from a distribution with parameters, such as the normal distribution. A nonparametric test is not based on normal distribution and is often based on the rules of probability and counting. They are usually slightly less statistical power than the equivalent parametric test.
2. The Kruskal-Wallis Test is a form of ANOVA that is a non-parametric test that does not assume nomality. It compares multiple groups based on ranking. The ANOVA does base results on assumption comparing multiple groups based on rank.
Step 1)
H0 = The feed is from the same population of turkeys.
H1 = The feed is from different populations of turkeys.
Step 2)
alpha = .05
Step 3)
Degrees of Freedom = 2
Step 4) Decision
Reject the null hypothesis when the critical value is greater than 6.98.
Step 5)
The null hypothesis is rejected as the value of all feeds are greater than 6.98. Therefore all feeds are provided by different populations.
Kruskal-Wallis Test
Median n Avg. Rank
11.30 5 8.80 Feed mixture A
11.15 6 7.67 Feed mixture B
11.90 5 9.20 Feed mixture C
11.30 16 Total
0.315 H (corrected for ties)
2 d.f.
.8541 p-value
multiple comparison values for avg. ranks
6.98 (.05) 8.56 (.01)
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