A graduate student realized that the depression study above in Question 4 should have had a placebo condition in which a third group was given a pill just as the people in the Drug condition were, but...

A graduate student realized that the depression study above in Question 4 should have had a placebo condition in which a third group was given a pill just as the people in the Drug condition were, but where the pill was not Drug D (e.g., a sugar pill). So she designed a new experiment with three conditions -- Drug, No Drug, and Placebo. To perform the experiment, the graduate student randomly assigned 18 people into the three groups so that each group has 6 people.   After one month of treatment, all 18 people were asked to rate on a scale from 1 to 7 how depressed they felt, where 1 = not depressed at all and 7 = very depressed. The following are the data:

Using an α-level of .05, perform an Analysis of Variance (ANOVA) to determine whether there is a difference among the three conditions. Specifically, answer the following questions:

1. What is the within condition degrees of freedom, df_within?


2. What is the within condition sum of squares, SS_within?


3. What is the within condition mean squares, MS_within?


4. What is the between condition degrees of freedom, df_between?


5. What is the between condition sum of squares, SS_between?


6. What is the between condition mean squares, MS_between?


7. Calculate the F-value for this experiment.


8. Using Table F, choose the appropriate critical value of F for this problem.


9. Based on the relationship between the value of F you calculated in (7) and the critical value of F you chose in (8), can the researcher conclude that there is a difference among the three conditions?