To see if brain stimulant affects test scores, we randomly assign subjects to three groups of five individuals each. One group receives a high dose of the stimulant, another gets a low dose, the third receives a placebo. Then all take the same test scaled on an 8 point basis. The individual scores are:
|
Placbo
|
Low dose
|
High Dose
|
|
1
|
8
|
6
|
|
3
|
7
|
5
|
|
2
|
5
|
3
|
|
1
|
4
|
3
|
|
3
|
6
|
3
|
Use the appropriate technique to determine whether there is at least one or more differences among the groups. Do we reject the null at the 0.05 level? What is the effect size? Write up the results.