A team of international psychologists was interested in studying aggression among adolescents in Sweden. The team devised an experimental paradigm in which participants played a computer game against an opponent. When the opponent made an error, the participant was invited to âpunishâ the opponent by exposing him to a blast of loud noise. The duration and volume of the noise blast were combined to give a measure of aggression. A total of 60 participants were tested using this procedure. Then, they were given feedback about their performance in the game. One third of the participants received negative feedback, one third received positive feedback and the remaining third received neutral feedback. Finally, the participants played the game again and their level of aggression was measured using the same method as before.
Conduct an ANOVA to determine whether the post?feedback levels of aggression are affected by type of feedback. (2 pts)
Participants were randomly assigned to each of the three feedback conditions, so the pre?test scores for these three groups should not differ. Test whether this is the case using ANOVA. (2 pts)
In light of the answer to the previous question, use the pre?test scores as a covariate and re?run the ANOVA from item 1 above as an ANCOVA. (2 pts)
Describe how the inclusion of pre?test aggression as a covariate changes the outcome of the analysis (7 pts)
Describe what the psychologist should conclude regarding the effect of feedback on aggression in this sample. (4 pts). Also discuss the generalizability of the results (i.e., to what population can the results reasonably be said to apply?). (2 pts)
Save and submit the SPSS syntax and output files used to complete items 1-5 above. The file names should begin with your first and last name followed by the homework number (e.g., John Doe HW8.sps; John Doe HW8.spv). (1 pt)