Question

For the graph below (Graph 1), answer the following questions: (6) 9 8 7 Treatment success 2. 1 0 CBT Family-based Low High

1. Is the main effect of type of therapy significant? (yes or no)
2. Is the main effect of level of motivation significant? (yes or no)
3. Is the interaction significant? (yes or no)
4. Based on your answers above, explain the results

1. Is the main effect of type of therapy significant? (yes or no)
2. Is the main effect of level of motivation significant? (yes or no)
3. Is the interaction significant? (yes or no)
4. Based on your answers above, explain the results

Answer 1

1.

For CBT, marginal mean = (2 + 8)/2 = 5

For Family Based, marginal mean = (2 + 8)/2 = 5

Since the marginal means are same,

There is no significant main effect of type of therapy. (No)

For high motivation, marginal mean = (2 + 8)/2 = 5

For low motivation, marginal mean = (2 + 8)/2 = 5

Since the marginal means are same,

There is no significant main effect of level of motivation. (No)

For high motivation, the change in success from CBT to Family Based is 8-2 = 6

For low motivation, the change in success from CBT to Family Based is 2-8 = -6

Since the changes are different, there appears to be significant interaction. (Yes)

2.

For CBT, marginal mean = (1 + 6)/2 = 3.5

For Family Based, marginal mean = (7 + 12)/2 = 8.5

Since the marginal means are different,

There is a significant main effect of type of therapy. (Yes)

For high motivation, marginal mean = (6 + 12)/2 = 9

For low motivation, marginal mean = (1 + 7)/2 = 4.5

Since the marginal means are different,

There is a significant main effect of level of motivation. (Yes)

For high motivation, the change in success from CBT to Family Based is 12-6 = 6

For low motivation, the change in success from CBT to Family Based is 7-1 = 6

Since the changes are same, there does not appears to be significant interaction. (No)