Question

Recent research indicates that the effectiveness of antidepressant medication is directly related to the severity of the depression (Khan, Brodhead, Kolts & Brown, 2005). Based on pretreatment depression scores, patients were divided into four groups based on their level of depression. After receiving the antidepressant medication, depression scores were measured again and the amount of improvement was recorded for each patient. The following data are similar to the results of the study.

Low Moderate	High Moderate	Moderately Severe	Severe
0	1.9	2.1	2.6
3.1	3.4	2.7	3.8
2.7	3	2.2	3.6
1.6	1.1	3.1	4
3	1.1	2.3	3.6
1.2	1.5	1.4	4

From this table, conduct an one-way ANOVA. Calculate the F-ratio and p-value. Be sure to round your answers to three decimal places. Assume all population and ANOVA requirements are met.

F-ratio:  
p-value:  

Answer 1

The statistical software output for this problem is :

F-ratio : 4.733
p-value : 0.012