Question

The following data represent the results from an independent-measures experiment comparing three treatment conditions with n=4 in each sample. Conduct an analysis of variance with α=0.055 to determine whether these data are sufficient to conclude that there are significant differences between the treatments.

Treatment A	Treatment B	Treatment C
13	17	15
13	15	13
14	15	18
16	13	18

F-ratio = _______________
p-value = ______________
Conclusion:

• There is a significant difference between treatments
• These data do not provide evidence of a difference between the treatments

η2=________________

The results above were obtained because the sample means are close together. To construct the data set below, the same scores from above were used, then the size of the mean differences were increased. In particular, the first treatment scores were lowered by 2 points, and the third treatment scores were raised by 2 points. As a result, the three sample means are now much more spread out.

Before you begin the calculation, predict how the changes in the data should influence the outcome of the analysis. That is, how will the F-ratio for these data compare with the F-ratio from above?

Treatment A	Treatment B	Treatment C
11	17	17
11	15	15
12	15	20
14	13	20

F-ratio = __________________
p-value = _________________
Conclusion:

• __There is a significant difference between treatments
• __These data do not provide evidence of a difference between the treatments

η2=____________

Answer 1