In: Statistics and Probability
The following data represent the results from an independent-measures experiment comparing three treatment conditions. Conduct an analysis of variance with α=0.05α=0.05 to determine whether these data are sufficient to conclude that there are significant differences between the treatments.
Treatment A | Treatment B | Treatment C |
---|---|---|
5 | 4 | 13 |
5 | 5 | 7 |
5 | 9 | 10 |
6 | 6 | 11 |
4 | 6 | 9 |
F-ratio =
p-value =
Conclusion:
The results obtained above were primarily due to the mean for
the third treatment being noticeably different from the other two
sample means. For the following data, the scores are the same as
above except that the difference between treatments was reduced by
moving the third treatment closer to the other two samples. In
particular, 3 points have been subtracted from each score in the
third sample.
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 |
---|---|---|
5 | 4 | 10 |
5 | 5 | 4 |
5 | 9 | 7 |
6 | 6 | 8 |
4 | 6 | 6 |
F-ratio =
p-value =
Conclusion:
1)
F-ratio = 11.6667
p-value = 0.0015
Conclusion: There is a significant difference between treatments
2)
F-ratio = 1.6667
p-value = 0.2298
Conclusion: These data do not provide evidence of a difference between the treatments