A psychologist was looking at the effects of an intervention on depression levels. Three groups were used: waiting list control, treatment and post treatment (a group who had had the treatment 6 months before). The change in depression levels over the time of the treatment was recorded (although bear in mind that only the treatment group actually got any treatment during this time). The SPSS output is below. Based on this output, what should the researcher conclude?
A) The treatment groups did not have a significant effect on the change in depression levels, F(2, 26.44) = 4.35.
B) The treatment groups had a significant effect on the change in depression levels, F(2, 35.10) = 5.11.
C) The treatment groups had a significant effect on the change in depression levels, F(2, 45) = 5.11.
D) The treatment groups did not have a significant effect on the change in depression levels, F(2, 45) = 5.11.

Question

A psychologist was looking at the effects of an intervention on depression levels. Three groups were used: waiting list control, treatment and post treatment (a group who had had the treatment 6 months before). The change in depression levels over the time of the treatment was recorded (although bear in mind that only the treatment group actually got any treatment during this time). The SPSS output is below. Based on this output, what should the researcher conclude? 
A) The treatment groups did not have a significant effect on the change in depression levels, F(2, 26.44) = 4.35. 
B) The treatment groups had a significant effect on the change in depression levels, F(2, 35.10) = 5.11. 
C) The treatment groups had a significant effect on the change in depression levels, F(2, 45) = 5.11. 
D) The treatment groups did not have a significant effect on the change in depression levels, F(2, 45) = 5.11.

Quizplus · Accepted Answer

The correct F-value to look at is the one with the largest degrees of freedom (df), which is F(2, 35.10) = 5.11. This F-value has a p-value less than .05 (p = .013), indicating that there is a significant effect of the treatment groups on the change in depression levels. Therefore, the researcher should conclude that the treatment had a significant effect on reducing depression levels.

A Psychologist Was Looking at the Effects of an Intervention