19.Aresearcher examines performance on an eye-hand coordination task as a func¬ tion of three levels of reward and three levels of practice, obtaining the following cell means:

Reward Low Medium High Low 4

10 1

Practice Medium 5

5 14 High 15 15 15

(a) What are the main effect means for reward, and what do they indicate about this factor?

(b) What are the main effect means for practice, and what do they indicate?

(c) Does it appear that there is an interaction effect?

(d) How would you perform unconfounded post hoc comparisons of the cell means?