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Laboratory animals were reared under three different conditions. The animals wer

ID: 3233106 • Letter: L

Question

Laboratory animals were reared under three different conditions. The animals were randomly assigned to each group. The following table shows the aggression scores for each animal. Does the mean aggression score differ for the three groups? Use a 5% level of significance. Make sure to 1. give the null and alternative hypotheses, 2. calculate the test statistic, and 3. give the conclusion (including a comparison to alpha or the critical value) to receive full credit.  

Rearing Condition

Extremely Crowded

Moderately Crowded

Not Crowded

30

30

30

25

35

30

20

25

30

30

20

10

15

20

20

20

25

30

20

25

10

10

20

10

10

20

10

20

10

10

Extremely Crowded

Moderately Crowded

Not Crowded

30

30

30

25

35

30

20

25

30

30

20

10

15

20

20

20

25

30

20

25

10

10

20

10

10

20

10

20

10

10

Explanation / Answer

null hypothesis:mean agression score are same for 3 groups

alternate hypothesis: mean agression scores are different for at least 2 of the groups

here test statistic =25.5472

3) as p value is less then 0.05 level of significance we reject null hypothesis and conclude that at least 2 of group have different agression mean scores.

Groups Count Sum Average Variance Extremely Crowded 10 285 28.5 16.94444 Moderately Crowded 10 205 20.5 30.27778 Not Crowded 10 130 13 23.33333 ANOVA Source of Variation SS df MS F P-value F crit Between Groups 1201.667 2 600.8333 25.54724 5.93E-07 3.354131 Within Groups 635 27 23.51852 Total 1836.667 29