Atticus is studying aggression among adolescent boys. He believes there is a rel

ID: 3179938 • Letter: A

Question

Atticus is studying aggression among adolescent boys. He believes there is a relationship between the level of interaction a boy has with his mother and their level of aggression. He has identified 5 boys who fall into each of the 4 interaction levels and upon assessment of a watching all boys at play for 1 hour, he measures their aggression scores on a scale from 1 (no signs of aggression whatever) - 7(extremely aggressive behavior). What is the independent variable (factor) and dependent variable for this study? a. Do the data suggest that there is a significant (a = .05) difference in aggression based on interactions with mom? b. What is the size of the effect for interactions with mom on aggression? Explain what this tells you. c. Calculate Tukey's HSD and determine which groups (if any) are significantly different from each other?

Explanation / Answer

No interaction:-26/5=5.2=X1

Low interaction:-24/5=4.8=X2

Moderate interaction:-20/5=4=X3

High interaction:-17/5=3.4=X4

X=4.8

SSA=5(5.2-4.8)^2+5(4.8-4.8)^2+5(4-4.8)^2+5(3.4-4.8)^2=9.75

SSW=(4-5.2)^2………….(3-3.4)^2=8.8

MSA=9.75/(4-1)=3.25

MSW=8.8/(20-4)=0.55

F-STAT=3.25/0.55=5.909091

ANOVA

Source of Variation

P-value

F crit

Between Groups

9.75

3.25

5.909091

0.006507

3.238872

Within Groups

8.8

0.55

Total

18.55

Tukey-Kramer:-

(X1-X2)=5.2-4.8=0.4

(X1-X3)=5.2-4=1.2

(X1-X4)=5.2-3.4=1.8

(X2-X3)=4.8-4=0.8

(X2-X4)=4.8-3.4=1.4

(X3-X4)=4-3.4=0.6

Critical range = Qa*MSW/2(1/nj+1/nj’)=4.05*0.55/2*(1/5+1/5)=0.4247

All except (X1-X2) are greater than critical range. Therefore, there is a significant difference between each pair of means at 5% level of significance except (X1-X2).